Harold,
I've recently installed the SRX11 expansion card into my G-70 and I echo your comments...VERY, VERY NICE. Though the G-70 only recognises only around 30 of the voices an the card (out of about 40 something on the card as shown on my Roland XV5050 sound module).
Back to the G-70, the card voices give a full bodied sound that I am very happy with. Understandable perhaps, given 64 MB devoted to the one purpose.
Keith