Yes, you can flash an older firmware version over a newer one. If you don't like it, just flash the original version back.
I wouldn't say V1 is "better" - just "different." It seems to use only physical channel numbers for QAM, ignoring all virtual channel numbers.
I guess that's "better" in the sense that it'll find everything, whether PSIP is present or not. (It still needs PSIP to set the time, though; so hopefully at least that part of WOW Cable's PSIP is correct.) But that also means it'll "find" all your scrambled channels too, and you'll have to delete them. Of course once you find out where all the clear QAM channels are, you can write them down, do a scan in OTA mode (which won't find anything on cable, of course - this is just to clear out all channels), then switch back to cable mode and manually scan in the clear QAM channels one at a time.
I'm not sure if V1 will even retrieve the channel names from PSIP, but you can always rename your channels once you scan them all in and identify them.
As far as alternative clear QAM tuners, there's the Channel Master 7001. I didn't like mine very much, though. They're expensive, yet lack a lot of important features, such as the ability to delete or hide unwanted channels. There's also the old Samsung DTB-H260F; much nicer if you can still find a working one on eBay. Finally, there's the PHD-208. All of these are expensive, though, and none has recording or media playback like the iView.