Hi Saxon,
I'd take just the two Tamrons because of f2,8 & autofocus. The 8mm Fisheye would be good maybe only for a couple of totals but the 17-70 is obsolete in this case. Camera set to AF.S with 5 AF-Auto, this is the best for tracking such event as people skating. Maybe you could do some nice panning shots; turn the SR off, find the longest exposure time (and the widest aperture) you can get for freezing the movement in front of a motion blurred backgrounds.

How did your skating session go?

Cheers, D

I was quite impressed with the X-5, got it for video recording. Tilting screen and the red record button are making it very useful. Works very well for general photography too. Great ergonomics, decent lens. Only thing where it suffers is handheld photography in low light. XG-1 dropped the tilting LCD, which is a shame and added nothing useful except (even more) telephoto range. I would recommend X-5 over the XG-1.