RE: Thumb trigger release 4 use w/ a D-loop??
I would say that before you plunk down the $$$ for a brand new release, you troll "that other site's" classified section and see if you can find a good used one.
A release, especially a Carter, will last darn near forever. A used one with some cosmetic scratches has no effect on the way the release works and will save you probably close to $50 over the cost of a new one.
I have found that trying to find a release that works for you is often times trying to find the right woman. The one you have been lusting after may not end up being the one that works best for you. I have gone through a significant number of releases looking for the one that works best for me, for a thumb trigger, the Carter Insatiable is it. For a pure BT, my Zenith Comfort 3D Plus fits the bill.