I have an IPV-5 and that thing was like a tank. It's really beat up and I normally use it to test out any new builds in case it leaks. Last time I tried, it wouldn't work, I may have to try newer batteries in it though, the ones that were in it were a bit funky, wrap-wise, that and maybe cleaning out the terminals.
That mod does look nice, but I'd be concerned about reliability too, at least until I have my own IPV figured out....
Anna