Me and my playing partner started playing Golf at roughly the same time, we've had maybe 4 lessons between us in around 5 years. Every change we make to our Golf game is very much due to what we read and see online. We were both pretty much at the same level (20 HC) with me winning some rounds and him winning some. Only a few things separated us for example, I would hit the irons and woods further than him, my putting was better, he was considerably better at pitch, punch and chip shots, he drives the ball more accurately than me.
He wasn't happy with the inconsistency of his shots and wanted to find out why so he began researching. He stumbled upon this "short thumb" grip and began looking at the pros and cons. He has now used the short thumb grip for 5 months and has literally won every round in the last 4 months. The main hold I had over him (the distance) is now gone, at the same distance from the green he is hitting 5 or 6 iron where I'm having to hit a 4 iron!! The consistency of his ball striking has improved massively and his chipping has got even better. Now I don't know if the short thumb grip is intended to increase distance but his distance has improved massively.
I've now had to change my putter grip to left hand low to keep ahead of him on the green. I tried to change to the short thumb grip but couldn't get the hang of it at all and it felt like I'd never played golf before. Maybe the short thumb grip is good for some people but not for others or maybe it's just down to my lack of patience.
I'd say if you were a beginner to golf it may be worth adopting a short thumb grip as it does seem to offer greater control. I'd advise everyone to use the left hand low putter grip!