While I agree it worked great for DA2, I don't know if that'd work so well for ME. I mean, for all it's RPG elements, a good portion of Mass Effect's game-play has always been third person shooting, which is still mostly player skill based. The only way to make the kind of incremental stats increase seen in fantasy RPGs meaningful is to start out as a brain dead, blind cripple who couldn't hit the broad side of a budong...and that really wouldn't be a lot of fun to play. Conversely, a fully min-maxed character would feel like playing with a one-shot-kill aimbot. Equally lacking in appeal as it takes away from the skill factor. I suppose something similar to the talent trees could be used on a much smaller scale, but it's not far off the current method of binary evolving powers.
What did feel odd to me was the universal cool downs. I understand the individual cool downs made biotic characters damn near unstoppable, but to makes little sense for say an sentinel unable to use 'overload' because they just used 'throw'. Perhaps grouping the overloads into power types would make more sense? As in you use a biotic power and all biotic powers go into cooldown, but any tech or combat powers remain available. That should stop specialist classes having too much of an edge while still allowing the hybrid classes some more flexibility.