I don't have any personal experience with those two engines, but I had a similar thread a couple of weeks back looking for a good engine for my Somethin Extra. The feedback I got then was that the Irvine 53 was the engine with the most torque if I wanted to do 3D type of flying.

You can read that thread here: [link=http://www.rcuniverse.com/forum/Irvine_53/m_2294463/tm.htm]Irvine 53[/link]

-tycho