I've played quite a few concert and tenor ukes, and one thing I always notice is that after a couple of minutes of strumming I stop caring about the size. If it's a good uke, I'm enjoying myself, and if it's a crappy uke, I'm not.

As far as sound goes, yes, there's going to be a slight difference between the concerts and tenors, but I don't think it's enough to lose any sleep over.

If you're really having trouble deciding, on final thing to consider is that concerts are generally a little cheaper than tenors.