Don't waste your money on a CT for your miter saw. Spend a couple hundred and buy a cheapo vac and a switch so it comes on when you turn the saw on. Or use an old piece of junk shop-vac you have around the house. That's what I did and it sucks fine. You gotta lose your mind to drop CT money just to keep it hooked up to a single tool. Buy a CT when you start buying other Festool tools.
The Kapex is great for DC and accuracy, but it's totally lacking in the ass department. It does not like to cut through 8/4 exotics unless the stock is dead nuts milled square. Even then it squawks on occasion. That's my only complaint about it...underpowered. But it was made for finish carpenters doing trim and casework, not for furniture makers, so I'm kind of whining when I don't really have the right to.