I haven't used the Milwaukee that's being referenced here, but I can say the PDC 18/4 Quadrive will be more than enough tool. The genius behind it is it basically has 4 gears similar to a manual transmission in a car - the lower the gear the more torque you have. The higher the gear the higher the speed. It also beeps at you when you've reached the torque limit in the current gear, to tell you to move down a gear for more punch. It's quite the drill - the kit I purchased also has the right angle chuck and the perpendicular handle for stability and more leverage. The noise the drill makes at full tilt through a Kreg jig is positively sadistic. That's not even discussing that you also get the hammer mode (or 'percussion' as Festool calls it).
The new version comes with the 5.2 a/h battery, which lasts forever as well - I basically used it throughout this past weekend and never put in the second battery once. It's still sitting in the charger and the original battery is snapped into place and when I checked the battery level it was still at 3/4's charge.
I can't say enough good things about this machine. If I was offered a clean switch between the PDC 18/4 and my dad's Lithium Ion cordless Makita hammer drill, I'd take mine all day. I used to think the makita would put hair on your palms, but it's not nearly as beastly as the PDC 18/4.