XA has user selctable infinite focussing. The RF patch can be a bitch to see at time though. XA2 is zone focussed in four discrete steps.
I think the shutter speed options may be a bit wider on the XA , but can't be sure. I am pretty sure both have backlight compensation. If not , lie to the camera on the film speed for the backlit shots, but don't forget to set it back once you are no longer in that situation.
I have both. They both work well. I tend to keep c-41 int he xa-2, and use the XA to better manipulate the aperture and shutter speed when shooting b&w.
I also have a pair of Minolta 35RC's and they act quite simialrly to the GSN, but with a slower lens, I think.
Standard slow shutter with a dead battery, and a real nimble one that can be quite quick when the battery is in them. Full auto exposure here.
I blank off one half of the old two battery mercury compartment ( one has a short piec of copper water pipe) and feed the other half with a pair of lr44 alkaline button cells to run the meter.
Steer clear of old Petri RF's. They tend to gum up, and are a challenge to maintain, with nothing but intermittent shutter jams for my efforts.