Using rings, TRX, or Blast Straps allows for a more natural rotation of the arms, so it feels much better if you have busted up wrists or shoulders. Beyond being more joint-friendly, setting the suspension device up wider than your wingspan makes it a lot harder – the straps will want to go out so you have to squeeze hard to counteract that force and keep them on the right path, which makes for a huge contraction in the lats.
Keep in mind that they're a lot harder than regular pull-ups, especially if you're strict on the form, so don't expect to hit your usual numbers, but expect your lats to be fried more than normal. You've been warned.
It's the sound you never want to hear when weight training. Sometimes you feel it immediately; sometimes you sense something happen but it takes a few hours for the full impact to hit you. Either way you've injured your back. The big question is, what do you do?