Few suggestions

[deadboy]

1. I'm against it because the rewards are already high enough and people would get too big boosts with these multipliers. The progress is meant to be slow so the players won't unlock stuff too quickly and stop playing.
2. Hard to imagine that it would be really used. Many forums got stuff like that (like the rating here e.g.) and it's used by the fewest. I think it would be useless ingame and everyone would ignore it.