Why? What gives you this boost?
HREAP allows a boost b/c traffic is locally switched rather than tunneled back to the controller. Tunneling back to the controller may not be the shortest/best path to the destination, or the controller may also be a bandwidth bottleneck in heavily utilized networks.
Will this only work for 1250s or can one use 1142s or the new 3600s? 1250s are big, ugly, heavy.
I have only tested this on1250 APs, and the Cisco documentation was written when the 1250 series was the only 802.11n AP they had. However, I suspect it is the same on all of their 802.11n APs. But I have not verified this. If you test it on another AP let us know your results.