if this ends up being a feature as compelling as achievements then I will buy a PS3... no question.
it might sound shallow but achievements and the associated aspects are the reason I play games as much as I do.
my xbox 1, ps2, and gamecube got almost no play time... I bought the 360 for some of the launch titles but achievements, % complete, gamerscore, and the community aspect of all of that through sites like xboxamerica, mygamercard, achieve360points, etc. are why I keep playing.
my Wii gets 0 play time, some of the games interest me a little but the lack of achievements and a competitive cross-game community I have no motivation to play those games the PS3 has some games that look mildly interesting but without a community surrounding only stat tracking analogous to achievements it again just seems like less of an experience.
I've said it before, if they do add that feature I will buy a PS3 but it has to be done right, stats that don't connect to a larger online community are worthless to me...
I'm also not about to buy a console based on the premise that such a feature will arrive at some point, they'll get my money when the feature becomes available and I can see that it's something that I want to be a part of.