I think the non-nav TCH only holds 20 voice entries, where the nav version holds significantly more. I don't have the figures at hand, though.
I have the non-nav, which means I have a Panasonic head unit rather than DENSO. I have mixed feelings on the stereo sound. It is OK at best. But I came from a Passat, where all the speakers were in the doors. Mid/Bass was low toward the front of each door. Tweeters were high near the front of each door. This means that the back tweeters were fairly close behind me. The TCH has most speakers in the front and rear deck. I think this location makes it harder to get a good sound stage. In 1993 I had an Altima that was similarly laid out. Adding dome tweeters at the far left and right side of the dash worked wonders. I'm not ready for any surgery on my TCH yet. Let other guinea pigs have that honor!
As for sound quality on phone calls, I haven't used it a lot, but I think it sounds even better than I had hoped for. People don't seem to know I'm on handsfree unless the windows are down. I'm very pleased!