i think its not easy to make a forecast how this pick-mode will influence the subsequent game. but i´m quite sure it will open new aspects of playing.
on the one hand, it could cause problems in low-level public game, where everyone wants to play clinckz, traxex or ursa. but who knows.
and on the other hand it will improve flexibility and strategy skills of upcoming dota player, maybe their teamplay skills as well.
therefore i suggest an cooldown of 15-25 sec before u can pick your hero.
so far to keep my mode suggestion interesting