In terms of the ongoing debate about Project M's acceptance among the smash community, my reply is simply not to bother with it for the time being.
It is definitely a topic we will have to deal with at a later date, but not now. For now we ought to keep this quiet. People who want us will seek us. We'll deal with these people when the project is finalized.
Things holding us back within the smash community revolve around doubt that a fan mod can do a better job than the original game. It does not matter if we claim not to try to be improving, that is the way we will be perceived, so the point must be dealt with on that level. We must persuade these people that being a fan mod does not mean we cannot do a good job.
This is best done, not by pointing out the obvious that counterstrike was a mod and was both great and successful (this would work in formal debate, but not in legitimately convincing people), but instead by asking them to give it a chance and consider what is possible beyond what the original devs intended that enables the game to have more depth than before.
Of course, remember who you are addressing, there are many people who oddly enough prefer brawl over melee or countless variations within both factions.
I believe that we could easily absorb a lot of the melee audience who were disappointed by brawl as a melee 2.0 and want brawl to be redeemed. I played one guy who plays brawl predominantly in project M and he loved it, he said it was like a blast from the past.
In general, things to encourage are open mindedness, willingness to try things out, willingness to consider alternative possibilities. Be calm and friendly. It's possible to convince, or at least make friendly anyone if you go into it with the right attitude.