A6 and R6 are the same construction, just different compounds. Many at the Runoffs were running A6's over R6's.
Tracking in general is much easier on tires than autoxing is. You aren't spinning the tires as much, it's less often you are sideways because it's harder to spin the rear wheels in 3rd or 4than middle of 2nd gear.
If it's really hot out, or you are running for say an hour or more at a stretch, I think A's would be fine.
V710's are more durable, but also more vague and I find slower on average... not shocking since they don't seem to care about keeping up anymore.
You also have to look at available sizes. Hoosier has more than Kumho does and if the tire doesn't fit the rim well than can hurt longevity too.
7x SCCA National Champion + 7x SCCA ProSolo Class Champion, 2009 SCCA ProSolo Overall Champion
I drive them, I compete in them, I sell more variety of brands than any other company.