Ya Rich, I have two of the Gamo .22's. I just did a chrony on the Shadow Supreme .22 yesterday. From memory the FPS was: 693, 697, 704, 710, 683, 698, 692....... So you are right about the FPS. The Shadow Supreme .22 is quite accurate and I am using RWS Superdomes.
Now my CFX Royal .22 is a different story.

It is the one I got from UK. I put it on the chrony yesterday and I was getting readings from the low 200 fps up to low 700's. I have not shot this one much since CDT and I changed out the spring and did a Turbo Tune. Maybe only put 50 pellets through it. I think it has been sitting for about 4 months now. That may be the reason for the weird numbers..

All in all the Shadow Supreme .22 does very well and hold a tight variation.
Gene