heatsink dissapation for universal controller board

DarwinStepperController_1_2 says the heatsink needs to be able to "handle about 10 degrees C or better". Is this the standard C/W measurement (ie need a heatsink with 10C/W or lower)? The heatsink recommended by [parts.reprap.org] from mouser has the following stats: 35 degress C/W @ 400LFM forced convection (or normal convection 44C at 2W). The heatsink is smaller than the one in the photos, which doesn't look good. Is the recommended heatsink sufficient? Will it "handle about 10 degrees C or better"? Thanks!

The heatsink stats for the 290-1AB are in the file [www.wakefield.com] (page 10 of the pdf, numbered 39)

Wow, the TO-220 package with no heatsink at all does 65C/W into ambient air with convection cooling. Even bolting a couple of bits of meccano will drop that to some 20C/W. The recommended heatsink must be tiny to achieve just 35C/W.

Does the board layout support getting a bigger heatsink (like an old cpu cooler, usually 1 to 0.2 C/W) and bolting all the hot devices to it?

If you want to know how to work it all out, [www.mcmanis.com] should help. An interesting result is that he finds that a mosfet rated for 169A can carry just 13.8A without a heatsink.

PS: the heatsink recommended by that link from jaycar is 6C/W with convection cooling.