string, hope that wasn't for my post. I tried to share the similarities and differences. Never said there was a right answer. If putting a speaker closer to a wall is important, he's possibly better off with the Quatro.
I guess it comes down to two questions:
1. Do you want more bass quantity and the ability to go a bit lower (not going to matter own 99% of your listening probably.
2. do you want better quality from 100hz on up? It's not night and day, but it is better in the CT version. As you said, you'd have to have both in your room and listen side by side to really hear the differences, but they are there non the less.
Johnny, as you said, is someone he should get in touch with and go over this system, room, desires and anything else that matters to him to figure out which one is best.
Also, I have to say that a new pair of Quattro's will sound better in the mids by a bit than an older pair as they constantly upgraded things. I find mine a tad warmer without losing anything. JMHO