Well, I'd heard that Monolingual had a number of issues on Intel Macs so I was wary of using Delocalizer in case anything similar cropped up. But I read a thread on the Delocalizer forum (http://forums.bombich.com/viewtopic.php?t=6901) which suggested that there weren't any problems and so went ahead and ran the app. With no problems - that I've yet noticed. The main issue with Monolingual seems to be that it trashes Rosetta, so naturally the first thing I did was test a non-Universal app (I used Amadeus II) and it launched without issue.

So, for what it's worth, Delocalizer still seems to work on Intel, and I saved 3600MB in the process. But at the moment my advice would still be to err on the side of caution; only go ahead if you don't mind re-installing everything. I didn't have to, but considering the possibility of a new install might help you make your decision from the right perspective.