If most of your tapes were originally recorded with the camcorder you're currently using to dub VHS to PC, I would agree with jjeff: you should continue with your current workflow and not bother with the expense of a Toshiba 620. "HDMI with 1080 Upconversion" is a playback feature of most DVD players/recorders and recent PC video hardware: it isn't involved in the digitizing of VHS. Once you have your VHS captured to either a DVD or a PC file, using the digital HDMI playback connection from player or PC to modern large flat-screen TVs results in better picture quality (compared to standard analog connections). I notice a significant improvement on my Sony and Samsung LCD TVs when playing the DVDs I've made from VHS using HDMI vs analog video connections.
The 620 and other similar units from Toshiba and Magnavox are the very last of a rapidly-dying product category, the DVD/VHS combo recorder. Being the last of their kind, they aren't exactly top-class, best-of-breed units: they are merely competent and OK for casual users. The VCR section is more fragile than any random ten year old Panasonic VCR you could pick up for $20 on Craigs List. Using the DVD to record from the VCR can be tricky if you aren't comfortable with the inherent limitations and restrictions of recording directly onto a DVD without a PC in the mix. There is nothing wrong with using a Toshiba 620, many here on AVS are happy with it, but for what it costs you really need to consider if it will offer any significant advantage over your current camcorder-to-PC hookup.
What is the end result you want to achieve with the digitized VHS? What file format are you creating right now on your PC from the camcorder? AVI uncompressed? Are you pleased with the result, and do you have enough HDD storage space for all the files you might create? If so, and again if most of the tapes were originally recorded on your current camcorder, then you should probably skip the Toshiba 620. Your present system preserves the VHS as a baseline standard video file which is future-proofed and playable on (or easily converted to) a wide variety of hardware (laptops, PCs, tablets, phones, media centers, BluRay set tops). By using the camcorder that actually made the tapes as your VCR source, you get the best possible tracking match between VCR and tapes, with less noise in the digital captures. As jjeff noted, the PC allows fine tuning and editing of the files if you desire, and multiple options for creating DVDs as alternative, additional backups.
Using something like a Toshiba 620 can offer advantages in speed and efficiency, but only within certain circumstances. The number one question would be what end result do you prefer? AVI files that can be easily repurposed for any playback device, and easily enhanced with current or future software and hardware developments? Or is your priority getting the tapes digitized ASAP, into standard DVDs, so you don't have to set aside HDD storage space on your PC? The trouble with going direct from VHS to DVD is that DVD is a lossy, compressed digital file format. You can get decent, watchable, but not "fantastic" digital copies of VHS this way. There is a great advantage in efficiency: load a tape, press the dub button, and repeat until all the tapes are copied onto DVDs. But the DVD will never be quite as good as what you can get from the PC, and the files on a DVD are much less amenable to improvement in future (since they've already been compressed to a lossy format). Untangling the actual audio/video files from the convoluted DVD formatting is possible, so you can in fact convert them for other devices or future processing, but you'd be starting with a compromised file.
It all depends on how you feel about these tapes. Are they priceless family videos? How priceless, really? Not to be cold-hearted, but many of us wildly overestimate the value of our personal family videos. We don't like to admit that they actually bore the crap out of us and anyone we show them to, or that the chances of us viewing them more than once every five years is pretty small, or that few of us are expert videographers: between the blurry focus and camera shake, there may not be all that much "quality" to be captured. If you tend toward this more "realistic" or practical view, then dubbing directly onto DVDs and filing them away can be a great option: quick, relatively easy, do it and forget it. But if you (or your wife, or your parents) feel these tapes are priceless family heirlooms to be treasured like diamonds, you may be better off continuing with your current method of capturing to PC. The AVI files common to PC capture just offer more initial quality and flexibility for later processing or conversion. Using a Toshiba or Magnavox DVD/VHS recorder, you get a passable DVD and no other options, which is perfectly fine if all you want is standard DVDs anyway.
You could also consider a dual approach, assuming you have a LOT of tapes to digitize and not all of them are personal camcorder creations. If you have, say, 300 VHS tapes, of which perhaps 50 are camcorder originals and 250 are TV series, movies, etc, you could continue dubbing the camcorder tapes using your PC hookup while dubbing the other tapes with something like the Toshiba 620. Our old TV recordings don't usually have so much emotional value that we need to make the ultimate digital copies of them, and if it came to that commercial DVDs and BluRays of the old stuff are cheap in chain stores (and far better quality than we could ever make from VHS).
Or, forget everything I've said above and just wing it. Instead of the Toshiba 620, go to WalMart and buy the Magnavox ZV427MG9, which is exactly the same recorder with a couple of added minor features. WalMart has an incredibly generous return/refund policy: you could experiment with the Magnavox for a few weeks and decide if the workflow and resulting DVDs satisfy your needs. Personal testing with your own tapes will give you certainty, recommendations on forums are only a rough guide. If you aren't bowled over by the Magnavox, you can easily return it and get your money back, and keep going with your camcorder-to-PC system. The Toshiba is no better or worse than the Magnavox, they come from the same factory based on the same overall design, but the Toshiba is usually sold by stores that are not that flexible with hassle-free returns. With this particular recorder, opting for the Magnavox version to get the WalMart return policy is the safer bet if you aren't quite sure you'll be happy with a VHS<>DVD combo.