Nice demonstration of a gri gri working well herehttps://www.instagram.com/p/CHYCn9_D7tP/?igshid=rh973tzd1r8b
I like a shunt for the start of a project/hard moves/ short route. You can go up and down easier than on a micro traxion. Descending on a MT feels horribly sketch. I've never got that on board with the gri gri train. Great for abseiling and trying moves if you're just inspecting stuff, but very bad for the elbow tendonitis trying to move upwards. For anything less than 15m a shunt is ideal (although this isn't how they're meant to be used).
Shunt/Grigri/MT Pro's and con's (just my opinion, JB and Bonjoy will have a better idea)Shunt: kind to the rope, pays out smoothly if rope is tensioned. Grab it and you're fucked, potentially the same if the cam arm hits you or the rock. Hit a backup knot at speed and it will open up and release pretty easily.Grigri: kind to rope, bit of a bastard to pay out rope. Harder to defeat mechanism than shunt.MT: best movement, looks scary but much less likely to develop slack so is probably the safest. Cam release is double movement so very unlikely to happen by accident.Also, learn to transition, then you can pretend you are a cool caver type rather than a boring climber with no real clue.
Always put a knot in. A device might break hitting a knot but my money would be on it not.