i've got a maximum with fan in my g2r revo (shorter than the big maxximum and higher kv) on 4s and it runs really NICE... i can't imagine needing anything more, wheelies at almost any speed... i've run it with a mamba max and a quarq with no issues... as far as support www.icare-rc.com is my contact and they in north america so no issues there... i don't know why they're not more popular here either... you've got 3 to choose from... they are pretty popular in europe