If the extra money and storage/transport are not an issue, then I'd say definitely go with the .60 for a couple of reasons. One, as stated before, it will be MUCH easier to see in the air, and should land much easier (I believe the wing loading on the .60 is equivalent to the .40). Also, that .61 engine will fullfill your second plane wants and desires much better. That is, of course, if you take the stuff out of your trainer to build your second plane. You might not want to do that. Evolution engines are great engines. The .455 that comes on the .40 size is a good one too! Both of those RTF kits will come with a 4 channel, analog JR radio. I replaced mine as soon as possible. Mainly because I wanted a computer radio, the quattro that it comes with is a good radio. I kept it for my buddy box. If you're looking at the ARF version, then you will have to supply your own radio kit and engine.
Good luck!!!