I bought one by accident the other week. Just sold it on as it is for a bike I am building for someone else but as we all ride each others bikes it will get confusing! I can see why people love it as it does make more sense and I have always wondered why you use your right thumb to shift down but your left thumb shifts up.
Kind of wish I had kept it to put on my 29er now.
I think one reason that conventional makes sense is with shifters that can do multiple shifts on the thumb lever. If you suddenly find yourself needing to jump lots of gears up you can normally just change the front ring nicely without any load. But if you need to switch to a much easier gear and are under load then it is much easier to do a single big multi-click up a couple of cogs on the cassette with your thumb
I do fully get the attraction though. Shame the multiple click lever design won’t work in the release tension mode as it only really works on a tightening action.