Wow, I've got a .46 in mine and it gives me all the performance I can handle (though it is only my second plane). I'll bet that .61 will really pull it around.

Beefing up the landing gear might also be a good idea as Jim suggested. I've unfortunately torn the gear out of mine twice now, but I must admit they were both less than spectacular landings. Thankfully, in the stock configuration, the gear will tear out cleanly without damaging too much of the airframe.