I'm not sure. If you start using smart pointers in C++, you can get the same problem: instead of a GC pause, you get a cascading delete pause. To eliminate it, you have to devise a smarter memory scheme, at which point you probably don't underestimate the determinism cap.

Also don't forget that garbage collectors can often be tuned. Granted, many of them suck, but a generational, incremental collector whose parameters can be tweaked? Much less room for pauses.