Altus, this suggestion will encourage people to play on ptp more and more.
There are a lot of ways to lure players to your server. Some of them are oriented to long-term effect, others are not; some are 'dirty' (like viral marketing), others are not. Of course, I don't mean that the way you've suggested is bad or dirty, no, but its potential effect and profit in terms of increasing the amount of players who actually play the gamemode is very dubious, and I don't think we are so desperate in terms of players' count to promote our server by any dubious ways in excess of the ones that are already being used.
I mean, if a player joins our server to play 4 player duels, it doesn't mean that he will spontaneously desire to play the gamemode, but the outflow of our current regulars from playing the gamemode will be slightly more noticeable. I don't want it, that's why I say 'no'.
And to be honest I also don't want our players' count to grow significantly at the expense of players who just randomly wander through different events, like it often happens on freeroam servers. Sometimes, when the amount of hatred decreases, our server can be very homelike - huge freeroam servers totally lack it, and none of them has left anything in my heart.