Hi Tom,
Yes I have My 1090T has gone all the way up to 4.8 ghz with a 3400 CPU/NB - However the main difference you get from AMD chips is increasing the CPU/NB as opposed to the clock speed - makes the system a lot more snappy.
the 1100T already has quite a high clock speed as it is, so if you were thinking of playing with it, do the above, with a crosshair IV motherboard I pop the CPU/NB volts to 1.32 and then increase CPU/NB to whatever i can get stable