I think that all of the planes mentioned are great planes. I have not personally flown the Giles but have seen it fly, and yes you do need to have a good engine to make it perform well. This is about true for all planes. If you have a crappy engine, then it doesn't make the plane.

Now, I have flown the UCD and I have to say you won't have to upgrade to anything after this!!. Just like the Somethin' Extra, on low rates, and small throw, the UCD is a very docile and elegant (for use of a better word!) plane....and then like I said, when you upp the throw, and get on some high rates, it is a very docile and incredible plane. I would say go with the 60 size, but if you can't, then the 46 also flies very well. It's just like the Funtana I'm going to get, I would love to have the 60-90 size, but it's just the engine that I can't afford right now. That same thing holds true for the 46 and 60 UCD. The larger plane, even though it doesn't cost that much, will cost you to have a larger engine to power it yet also have some fun...

Hope you have fun with whatever you choose to get!!

~Michael~