ARSR - Can't wait to play it :D
I prognosticate that playrate will be lower then Nemesis Draft and even lower then EUNE Draft Pick. :D Why?! Why do you make such mode as RGM?!
It would be fun to have such feature in champ select. Much like Random in RTS (StarCraft) or fightings (Mortal Kombat) works. You press a button and random champion is selected for you. With or without semi-random nature. E.g. if you have bot - you most likely to get marksman.
But why in LoL as a full game mode? It cannot bring something fun apart form weird team compositions. And it will get boring really fast. I think there will be a peak of plays first day (curiosity and confusing it with ARURF) and then it will drop significantly with really low playrate at week two.