|Evan's point in his article is that the Bravo scaler is not top notch, you are buying the Bravo for the DVI capability not the scaling capablilty.
Your point is well taken, but unless I'm misinterpreting the remarks of Bravo users in the DVD Hardware forum, many seem to be pleased with its scaling capabilities as well, especially on larger screen HD digital displays using 720p.
One possible reason for this could be the difference between video-based (60field) vs film-based (24fps) material. Film-based material (most commmercial DVDs) is easier to scale because reverse telecine (another form of de-interlacing) can be used to restore the original full progressive 24fps. Scaling the resulting progressive frames up to higher resolutions is much less complicated than scaling interlaced video content where the missing scanlines have to be filled in.
The steps for film content probably go something like this:
Reverse telecine 480i->480p24
Scale 480p24->720p24 or 1080p24
Re-telecine 720p24->720p60, or 1080p24->1080i
Since the scaling step with film-based material can go progressive->progressive, better image integrity can be maintained with fairly simple scaling/resampling routines. This is why even fairly inexpensive DVD scalers may be able to do an adequate job, especially for 720p which is the most straightforward. There'll certainly be many variations in how this is implemented though, some more successful than others.
The improved PQ of DVI (as others have mentioned) is also an important issue to be sure. If the display can pass the DVI's digital RGB directly to the screen with no digital-to-analog conversion, a noticeable improvement in PQ results. Until the recent release of the DVI players, many users of higher-end displays have been stuck feeding their expensive digital screens with inferior YUV analog sources. Hence their elation at finally being able to deliver a true digital source at the display's native resolution (in many cases 720p).
I can't disagree that an HTPC offers some greater flexibility in terms of tweaking the scaling quality, and customizing resolutions for different types of displays. But with the exception of new MyHD-120 users, most HTPCers are limited to feeding analog YUV to their HDTV displays. It's possible to go directly from a graphics card's DVI to an HDTV's DVI input. But few users seem to have found the magic combination of hardware, software (including HDCP countermeasures), resolutions and timings to get this to work well for their particular display. Good DVI DVD player/scalers will potentially take care of all of this out-of-the-box.
In any event, which approach to scaling (HTPC, the HDTV display itself, or a DVI DVD player) works best for any given user may depend on a variety of factors.