No denying a ball rolling slowly may veer off a little.
Bear in mind the rack's only taking up like 20 square inches out of 5,000. So the odds are pretty slim after a solid break. You can almost always lift it off the table. The few times you can't, usually just one ball is keeping it anchored down. If your opponent agrees you can just lift that ball.
The tradeoff (perfectly tight racks in exchange) is totally worth it, if you're thinking of making the whopping $15.00 investment. Remember that a loose rack affects the roll of the balls too, just at the start of the game instead of later on.