Here's a great link to some testing of both the "T" and "D" versions of the 2408-21 (BP21), 2409-12 (12T), and 2409-18, all of which are some of my favorite motors for price and performance. Not very efficient motors but the 18 isn't all that bad and it's a great low RPM/high torque motor for slower builds or even 3D. The 12T is a nice combination of both speed and torque, sort'a motor that's got it all...real good speed but the ability to be a torque monster for unlimited V. Think of the BP21 as a little brother to the 12T, perfect for planes under 20 or so. Again, the "D" versions are the same specs but just built much better. Get those if you can.
This page and the following one have reviews of various "T and D" versions.
http://myhobbycity.com/showthread.php?t=345&page=2
PS- Note the mph and prop choices for the 12T. I think he even tests a 9x6 on it. [8D] I've got to sit down and read this thing on paper...