I'd HIGHLY DOUBT the JB3 limiter is structured like a compressor/limiter, but more along the lines of an AGC circuit (probably spun off its "volume normalizer" for making tracks sound the same loudness.
The EAX stuff is actually not "too bad" (all things considered), but most people run these off outboard A/D's, so the line in/pre-amp/levels circuitry isn't a consideration. I'm sure it's not going to be as "musical" as say the soft-knee limiter on the MiniME. It wouldn't be the type of thing I'd depend on, in place of setting proper levels though.
It appears that Creative put the recording abilities in as an afterthought, as they sure didn't spend much time DOCUMENTING them.
Rick