I have been testing our V3700 - so far pretty good, though I am having some trouble with sequential read speed. Write speed and random is fine, but sequential SINGLE threaded read seems to max out around 68MB/s no matter what. My old MD3000i with a similar setup can run a little over 100 (theoretical being around 120 on gigabit).
MPIO seems to work great, and the web interface is smooth and quick. I may call IBM to see if they have some advice for me. I think it may be a TCP fragment or ACK issue (I've tried jumbo frames and Delayed Ack).
Have 19 600gb 10k 2.5" drives and 3 200gb SSD's to test with. Running the included 4 gigabit ports (no additional ports).