I agree that there are some significant similarities to the VA-series in the G70 (naturally, just as a T2 has quite a bit in common with the T1) but there are some VERY significant additions. First of all, the VK Organ mode. A HUGE improvement over previous Rolands. Then the GrandX piano from the FantomX is my favorite hardware piano, these days (warmer than all previous, and more dynamic than even my K2500 with Piano card). V-Drums, not sure if they were in the VA series..?
But the majority of improvements have come in the OS. The VA series wasn't exactly bristling with realtime controls, and those have been significantly improved, and now we have a full, user definable OTS system linked to each style, pretty close to comprehensive control systems (user definable), and a very effective touch screen and full set of sliders.
I know quite a few of the ROM styles hark back to the VA series, but there have been a considerable number of new styles from Roland and MidiSpot that may not have been loaded into a store floor model.
You MIGHT want to wait for a while and see if Korg bring out a new PA TOTL arranger using the PA800 engine. Significantly better polyphony, significantly better sampling (the PA1X only supports up to 32MB, which doesn't go very far, and loads VERY slowly) and an improved synth engine. If sampling is the main thing you look to get, perhaps a rack used Z4/8 Akai might work better... Better library, MUCH more RAM (512MB, I think), and it's own polyphony. Just MIDI into it from the VA.
If the VA-7 has lasted physically in good condition, it MIGHT be worth holding out, at least until summer NAMM, or even winter! You ARE going to miss that key-bed, though!
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An arranger is just a tool. What matters is what you build with it..!