When the idea was first proposed I was actually opposed to it. But after talking with some friends I think this idea has quite a bit of good and very little bad.
I think this system will give guys with years worth of cardio (Diaz brothers, Guida, Edgar, Fitch, etc) a boost as these guys usually look better in the 3rd round than they do in the first.
I think it gives strikers a better chance against wrestlers. If Kos had gassed himself trying to hold down Daley then his TD's would be easier to defend and Daley could have tried to finish it with his fists. (An example, I think this fight could have gone 100 rounds and it would have been the same result.)
I think it forces guys like Rampage, T.Alves, BJ Penn, etc, to have better cardio.
One of the big cons for me, and it has been pointed out, is that it kind of blurs guys records. Fighter A fights in 8 fights, 4 of them are main events thus 5 rounds, he finishes all 4 of them in the 4th or 5th round. Fighter B fights in 8 fights, all 3 rounders, goes to 8 decisions. Assume they are the same caliber fighter fighting same caliber opponents. Chances are Fighter A gets the bigger fights or championship fight and gets known as a 'finisher' while Fighter B gets known as a guy who always goes to decision. There records are only comparable in the sense that 'as of 3 rounds all 16 fights were decision fights'. It doesn't make for a compelling argument.