RE: back tension release -trigger or no trigger
It really depends on you.
If you are suffering from any sort of target panic, a BT release (no trigger) will help you in getting that sorted out. That said, it takes much more work to get good with a BT release than with any other type. The other issue is that with a pure BT release (no saftey) you will undoubtedly end up punching yourself in the face at least once during your learning process.
If you decide that this is the way to go, I would recomend starting out with a BT release with a saftey such as a TRUBall Sweet Spot, or Carter Solution 3.
As to which is the best, It really depends on you. Each release is shaped a little differently, so it is up to you to find one that feels good in your hand.
For a pure BT release, I use a Zenith Comfort 3, and absoloutely love it. The fit and finish is top notch and it's functioning is flawless.
For a triggered hand held, I have Carters and TruBalls. I find that for me, the TRUBall Trail boss just seems to fit my hand a little better than any of the Carters. The Carters are great releases, with top notch customer service, but for me the TRUBall is what works.