The biggest issue with these diy builds is that they need the mechanics to be inside the lens - which is not necessarily a bad thing, however it severely limits the lens choice for the system, and introduces additional cost (you basically need to buy a shutter with every lens). The scene has definitely improved over the years, there are a number of very interesting x-pan-like builds which have been made possible by advancements in 3d printing.

I'm looking forward to the day someone figures out how to modify a full frame shutter assembly (plenty and cheap on ebay) to work with medium format film.