This has been discussed extensively in some other threads. As far as blu-rays go, I don’t think there is any proof that amateurs/faneditors/we have ever gotten seamless branching to work without pausing for a second or so. There have been some great ideas posted, but so far I am not aware of anything that has worked (including any of the tests I have done). Possible to do it with DVDs, though.

The other thing that comes up is matching sources as far as quality, color, grain, etc. Could get quite messy depending on how many options you plan on making. But I see the reasoning behind doing so. When it comes to semi-specialization, pretty much no one is going to agree 100% about what cuts to use. Personally, I think re-composited shots that use the original elements are great, and show off the art or model work. But if someone else loves recomps but also Mos Eisley dinosaurs, that makes for quite a different film.