I have a Dan-Inject, been really happy with it. It operates the same way as the the PneuDart, adjust for range with the manometer, but the darts are totally different. The PneuDarts are one time use, the Dan Inject I can re-use. I pressurize them with a syringe. I can use the PneuDarts in my DanInject with the larger barrel. I have used it to capture a couple animals and also to give some Lutalyse.
I picked up a laser range finder in the Bargain Cave at the local Cabelas, it helps a lot if you have a chart telling you what to set your manometer to. The Dan-Inject can do up to 3cc with the 11mm barrel and up to 10cc with the 13mm barrel.
I also have a MediDart bow for larger dosages (up to 30cc), which I have not needed yet. Figured it would be good for Tetradure, fortunately haven't needed it since I bought it a year ago.
Animals don't associate the dart hitting them with you, it is low stress. When you use it to capture, you want to leave them alone after you dart them until the drug has done its thing.