Thiel 1.6 vs. 2.4 vs. 3.6 using NAD c372

I am considering a combination of Thiel speakers and a NAD c372 integrated amp. My questions are:

1. In a fairly small room (16' x 13') with the speakers unfortunately along the longer wall, what are the thoughts about the Thiel 1.6, 2.4 and 3.6 speakers?

2. Why are used 3.6 speakers now offered in a similar price range as the used 1.6 models?

3. How do you think the Thiels will match up with the NAD c 372 integrated amp? Which of the three speaker models might match up the best, if any?

Thanks