Hi Alan,
the early 6.0s have been deferred quite quickly. It looks that both 6.0.199.4 and 7.0.98 are totally survivable.
The most stable of all is the 4.2.209 but if you want the new features/APs support, I'd say 6.0.199.4 is the one.
But this is a personal opinion and each version might contain bugs that you will encounter or not, there's a bit of luck as well :-)
Nicolas
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