T-5 vs. Standard Fluorescent... also T-6

I read the last thread concerning CF vs. fluorescent, and I did learn a
bit. I was wondering if anybody out there has any experience &
knowledge concerning T-5 units? I've seen these suckers in action and
they seem to be much brighter than standard fluorescent, with much
lower wattage and operating temperature. I was wondering what the
advantages & disadvantages are compared to standard fluorescent bulbs
(besides current cost obviously). I was also wondering if anyone has
any experience with those quantum T-6 bulbs that can operate in a
standard fluorescent fixture?