Don't waste money on a gimmick rack. Get something well-made out of wood or heavier plastic, and save your money.
The trouble people have with the head ball rolling off, or balls not freezing is almost never due to the rack itself. As long as you're breaking the balls with any amount of speed, you're going to develop an indentation where the cue ball pounds the head ball down into the bed of the table. And, you're not likely to ever have a set of balls that are all identical in size and perfectly true in shape. Even if you do, they won't stay that way forever. Sure, they're going to be remarkably close, but you'll be hard pressed to find exact matches. Those tiny differences make it difficult to freeze every ball together. Add in the texture of the cloth, and you're in an even tougher spot.
And as long as all of that is messing with your rack, why spend $100+ for imperfection? At the US Open, with brand new tables, and supposedly the truest triangle rack available (the Delta 13), it still took several minutes between racks to get the balls frozen.
It seems that the bottom line is, unless you plan to train your table (as you might for the Sardo Rack), you're going to have to work to get a nicely frozen rack no matter what you use. And if you train your table the right way, you can probably rack with your bare hands.