Anyone is better than Clemente, he totally held the band back from realizing their full potential. Very weak stuff.
If Mickelson ends up doing the CD I doubt he'll get a ton of influence since Lombardo was capable of much more than he did on The Gathering. Either way, I thought The Gathering was their strongest effort since Souls of Black, so I hope the next one is even better.
Tempesta's pretty good, too, but Mickelson blows the rest of the guys mentioned here out of the water, including Hoglan and Lombardo. But they are both great drummers, too.
Regardless of what happens, I hope Allen gets all his issues resolved so he can keep playing in either Testament or maybe get Sadus going again.