Basically, having 441 allows for 9 full attacks in the 20 second period of your 2 best dps buffs. Thus allowing for one more attack just before the cutoff and one more defiance stack respectively. So that is what is to gain at 441 skill speed. Not including the direct effect of faster skill times. With 450+ (I use the bravura and some ss+ slaying accs to keep me at about 9k hp while maximizing dps) your gcd can get to 2.39 secs. So yeah I say i would use skill speed up to 445~ then throw up your other stats behind it. I find that it all adds up to not only a mit buff in the end... but great a dps buff. With ideal conditions you can get anywhere from 140-150 dps even with defiance on. This is assuming you meet the min accuracy caps and at least i100~