In regards to AF speed and accuracy Sonolta, the A200 does really well in even decent light. For my experiences, I found the A200 to keep up with the A700 in terms of speed and accuracy (sometimes more accurate than those with back/front focus issues) which is pretty impressive considering it's price. When light dims to about indoor levels (say at home... typical lighting) the A200 has a bit more trouble to lock onto the center sensor whereas the A700 will make a lock. I presume the lighting at the arenas should be sufficient for the A200 which would make it a good candidate as a back up to your A700.
I have both and for normal shooting which includes landscapes, portraits, macros, and the occasional family shots and weddings, the A200 doesn't feel like a camera where I sacrifice much, if at all. In fact, prior to V4 firmware, I preferred the A200's higher ISO output to the A700s from ISO 800 and up.
Be interesting to see what you think of the A200. MLU to me is a feature they have to have in that camera, and should have. I can live without DOF preview just fine, but MLU (amongst many other items on a list) went directly to Sony's alpha design team by me as requested as suggestions to improvements and criticism's (and even some praise was sent) for all the Alpha lineup

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Carl