You don't monitor through your near-fields when in the studio? Wow!

You wouldn't believe how good your G70 can sound through a really nice pair (I use Mackie HR824's). Compared to that, all keyboard combo amps are a POS, IMO...

The problem, as I see it, is that most combo amps are designed for onstage monitoring, where they are doing spot reinforcing for the ambient spill-back from the main PA. As such, they are rarely designed to be flat spectrally, but to emphasize the frequencies that need boosting for good clarity in a stage situation. This doesn't necessarily make them the best candidates for situations where they are your ONLY source of sound.

You CAN work around this (sort of), but I prefer to just use full range PA stuff (it doesn't have to be big, just FLAT) for gigs, and my near-fields in the studio. Once you let your ears readjust to the less 'hyped' frequency response, It's a lot easier to get a Part mix that translates well to different systems (just like mixing a CD - you wouldn't do THAT on a K4, would you?!).