With the 8 bit (output color depth per pixel) manipulation of older HTPC's (with Ge-Force 2 chipset based VGA cards) doing the scaling and de-interlacing duties, the image was less than it could have been, but if properly chosen overlay (DVD pixel ratio vs that of the chosen output format) ratio's where chosen, the results where superior in most respects-when related to analog input standalone scalers.
With the advent of 10-bit VGA chips being now in the realm of HTPC's, the question of proper scaling at any pixel ratio (width x height) becomes much less of a problem. This means that the ratio or scanning rate that best complements the display device of choice can be chosen instead, with very little or none of the possible artifacts rearing their ugly heads.
For instance, I just tried out ATI's latest VGA card. It has very clean output at my chosen scanning frequency, of 89khz. I run at 1920x1200, and DEMAND a clean image be presented to the PJ.
You have to understand, the actual device that does the work in a given scaler (most of them) is a single chip, or limited chipset,and that item on it's own, comes in at a very reasonable cost, definitely less than $100. More like about $30. The rest is extra money spent on ancillary parts and whatnot (chassis, power supply, etc.)
It should be clear that the choices for internal components are actually QUITE similar and limited. There are only so many chipsets and components to go around, so differences are minimal between scalers,and will not only remain so, but will eventually seem to disappear. The advantage to HTPC(besides the hassle as a drawback) is the near instantaneous upgradability.
Scalers, the reality being that they are NEARLY the same device these days (I am not talking about re-badged custom HTPC's), either) are increasing in their ability to quickly upgraded. If flexibility is a concern, as well,and you are competent with PC's, then the advantage of HTPC comes to the fore in a very hard way. You are suddenly in no way subject to the vagaries of fate that may visit a given manufacturer, when it comes to servicing. True, you are on your own, but your avenues remain open, and ever changing. Sorta like the stock-room-floor of scalers, so to speak. Things happen NOW.
With the stand alone scalers, most of your upgrades are possible,and happen, and are there.. but REAL changes tot he scaler demand a complete new purchase of hardware. They may be user friendly in many ways, but this advantage can and generally comes at great cost to the end user, as far as initial purchase price goes.
As you move upwards in pixel density capacities of display device, the HTPC really shines as a viable choice,as the increased densities (lets say 1280x1024 and above) lessen any tendency towards image presentation problems. Since they have a lower bit depth than many scalers (true scalers, that is.. many have a decent bit depth when manipulating video) high scanning or output frequencies (or pixel densities) are to their advantage. I suspect that most new scalers are in the 10-bit-per-pixel depth at this time. The Snell & Wilcox scaler is at 12-bit depth, and is considered to be very, very good.
When a new round of chips come out, you will see a new round of scalers come out. Re-purchase may be the requirement, due to the fact that a whole motherboard replacement in the scaler may be the minimal requirement. In a HTPC, it's anew VGA card that needs to be purchased when this happens. This happens at a faster pace than the Scaler market, in the general sense.
When the PC market finally realizes that their only place left to expand is in the Home theater market (as they have reached saturation in the new-PC marketplace, and are in replacement mode as of recently), you will see this beast begin to take off. Imagine the juggernaut of the PC marketplace attacking your home theater. The ONLY thing holding them back to some degree is the manipulative practices of the software (viewing material) industry as a whole. You see, the digital-level upgrading of the Home theater or entertainment market space is nearly as huge as the PC market (in some ways), merely because it has YET to be actually serviced.
So, the PC marketplace can stave off stagnation if they pry their way into this space in a wholesale fashion. Digtially derived video intergrated systems for the 'average man' so to speak. But..the MPAA will have nothing to do with that. Let's see how this 'organization' fares against the PC industry. We are about to find out.
This was my round-about way of saying, 'no, I haven't done any comparisons'. I don't have access to those scalers. I could have an opinion to you in a matter of minutes if I did, I suspect. ( when I go to audio shows, I am tuned enough to sound quality, that I can accurately evaluate a speaker playing in a room well enough to judge it correctly from the hall outside, before I enter the room it is playing in) The differences should be gross enough to be quite visible and easily seen. It all comes down to 'precieved value to end users, vs. what they have seen and know of'.
A cheaper option may be in place, (HTPC's and the like) but.. are they (end user-purchaser) aware of the existence of such? The fact that I do not have any access to scalers does not nessessarily make my remarks invalid to any immediate degree. I have a largeish backgorund in the qualitive analysis of individual componentry and the parts (and ways) that a given piece of electronics can be executed or constructed. Basically, approx. 20 years of messing with gear in the whole and individual part level.