From sound samples I've heard of the Akai I find the sounds at least fairly similar, or at a minimum produce the same family of sounds. As far as "extraneous noise" I'm not exactly sure what you mean - the G5 can "fart" if there is more than one note being processed (which could just be a wobbling string or a fast run where you leave a note hanging). Otherwise it never produced noise and I never needed a booster pedal as the input/ output knobs always provided more than enough volume and fat synthy goodness. The tracking was awesome. However, I was required to get a bypass looper because it definitely sucked away my tone when bypassed.
Just keep playing with it. It's freaking awesome.
If you have both a Deep Impact and G5 have you ever tried running them at the same time?

Too ridiculous to even try???