Hi 575 & Extreme,
I agree with you on the inefficiency of the hot outrunners (
JS, Hoffman). They indeed are battery cookers.
I personally have a WM400 and a Wemo MF 480, both outfitted with the JS1400s - both are decommissioned. They are still good & stellar performers, and virtually burn out proof - but, they just draw way too many amps. (I plan to possibly use them for a homemade wind tunnel)
I have built a 2 new WM400s. 1 using a extra "cool" long can Velocity-RC "V2860-3700-Semi-Hot 3700kv 4s, 28mm motor" from EFFLUX RC - very nice EDF combo,
and the other with an ARC 28-58-1 3180Kv (for 5S) from Chuck's Hobbies - (installed in a HABU/foam version) - also very nice.
I have just a few flights on these since the weather this summer in central Texas has been so searing hot, I've stayed grounded since mid June.
Finally, I've done up a WM300 (60mm) with an ARC 28-47-1. Tested it on 4S in a Stryker (F-27C version), and it performed surprisingly, VERY well - almost, but not quite the performance of a 70mm, but definitely blows any other 60/64mm fan away by far (clocked at 110MPH out of mild dive with slight tail wind). An HET-RC Super Sniper is its new home - will maiden soon.
Update: Maidened the Super Sniper 70mm: no clocking/radar data, but it's sick/rediculous fast!
BTW, if you haven't flown any really fast airplanes yet, this shouldn't be Ur first one - get a Multiplex Funjet, get proficient with that first (like I was told & did) & be likely to succeed (like I did).