Interesting thread - a great deal of opinion, and very little user experience?!
I have owned a Darbee Darblett for a little over a year. It is the single biggest enhancement to picture quality I have seen. Its effects are incredibly good, and when dialled into the appropriate subjective level (50%-60% for me personally) I can't imagine anyone not being impressed by what it does.
Let me clarify, the Darbee processing is not an upscaler, nor is it purely an image sharpening system (nor indeed is it anything like JVC's e-shift - which also incidentally is excellent). It is quite difficult to describe the effect, but it substantially enhances both the detail level and depth perception of the image. The latter effect is very subtle, but has quite a noticable effect on the viewing experience, making blu-ray even more engageing that it is already.
The level of its effect is also counter intuitive in that it works better, the better the source material. The better the movie transfer the bigger of a percieved improvement the Darbee will provide, since it has a more clearly defined and accurate (in terms of clarity) image to work with. Conversely the lower quality the source material the lesser of an improvement will be percieved. It is therefore excellent with blu-ray, and less so with off-air boradcasts.
All that said I wouldn't buy the 103D to get it. The simple reason being is that you want it further up the video chain, so that all of your sources can benefit from it. You are therefore better off buying the seperate Darbee Darblett (which is only around £100 more than the increasein the Oppo price), which runs in line just before your screen/PJ. I'm sure some people may baulk at the extra cost for this 'effect' but I would suggest it can provide percieved improvements greater than doubling your screen or projector budget, so in context is exceptional value.
The Darbee tech certainly must be good enough for Oppo to jump in with both feet and include in it thier already excellent video reference blu-ray player, and somewhat rush it through in between generational changes in their range. In addition Lumagen (who produce some of the worlds best video processors for those on here that haven't heard of them) are also including the tech in their new processor range. I would be highly surprised if we don't see the tech appearing in some big brand TV's and projectors in the fullness of time.
In short, whilst YMMV, I would recommend anyone to give it a go, and save their judgements until they've tried it - distance selling rules dictate items can always be returned if you don't like the effect, but in all honesty, I cant' see many people not being impressed by it.