Sadly alot of people will be doing this several of us myself included will be really testing the game and reporting bugs and glitches/texure pop ups,ect. I find myself hardly thinking of it as "getting DLC for free or playing early" instead thinking of it being as a "beta" if that makes sense
I saw this so many times: I participated in betas for BF: Bad Company 2, BF 3, M.A.G., PS Home, Killzone 3, Ghost Recon: FS, Assassins Creed: BH, Medal of Honor and many more on PS3 and 360. I regulary visited the developers forums and reported errors or balancing issue but the problem is that almost no one cares about reporting errors/bugs/glitches and most of them just play the beta and contribute nothing at all. It's hard (if not impossible) to seperate these people from others who really want to help.. I find this very sad because of these people some bugs stay in the beta without being spotted until the game goes gold... even very obvious issues can't be fixed timely.