I'm having trouble trying to muddle out which one of the two is better. The bonus in rage converted to damage with Imp. Execute seems to be just a little under 10% but I seem (at least I feel like) I use it a little more often than MS. I'm not sure if that would change with the lower cooldown. Although the changes to Execute with 3.2 also seem to make it entirely reasonable to Execute over and over at the end of a fight. I will probably do some active testing on my own, but I'm not the greatest at number crunching, so I thought I'd check if anyone else already had.