Just wanted to post a follow up about the direction I went. I had ruled out the Ti15 as my "one drill to do it all". After handling the C and T series, I ended up choosing the new 4.2 T18 +3. The c just didnt feel quite right. My first impression after i receive my T was absolute amazement. The precison that i felt in such a powerful drill was awesome. One of my first projects with it was a handrail and posts in my house that i had been putting off for a very long time. I immediately realized 2 things: 1) i love the t18. 2) even with the centrotec quick change, i dont like only having one drill to drill and drive. I like havent a separate driver on hand. So i brought in my old m12 impact and continued on. A few screws that the m12 stalled out on we're easily finished with the T18.
So I then went out and bought the 4.2 Ti15 to be my driver. I was a bit worried about it due to less than rave reviews by several people on the FOG, but figured i had 30 days to find out for myself. I used it for about 8 minutes before i knew there was no way i was returning it, its great! It has performed flawlwssly for me for the past couple of months. The batteries might not be 18v, but they add to my pool of batteries that will fit the t18 and my cordless Carvex.