Yep, storm in a teacup time, again
Yes there are a bunch of different pianos in the G70, but only the GrandX comes from the FantomX. The rest are legacy pianos from the Sound Canvas and JV series era.
Most of them have too much hammer 'knock' and 'thump' (difficult to EQ out) and fewer samples. The G70 GrandX was one of the first 64MB piano sample sets to make it to an arranger, a true 4-way, mind you, without pedal down samples or resonance samples which are in more modern piano sample sets (but none of those have made it to an arranger, yet, AFAIK)...
Without being able to play one again, Ian, all I can say is that EVERYTHING I have sent you that has a piano on it, or anything at R-A.com done by me with a piano on it has ALWAYS used the GrandX. And the UltimateGrand frrom the FantomX at Purgatory Creek is exactly the same set and programming.
Have a listen to any of that, and tell me again if you hear any 'unevenness'...