My guess is that the OP has long since made a decision by now, but just to add my two bits:
The PDC 18 is, like most Festools, a beautifully-engineered, precision piece of machinery. It's both the smoothest-feeling and the highest-speed full-size drill I own, and its ability to blaze through lightweight materials is a real sight to behold. That speed also makes its percussive action blast through masonry: it's like a tiny handheld jackhammer. The wide range of available FastFix attachments also make it exceptionally versatile for a tool in its class.
Where it suffers, though, is torque. It is at best classified as a medium-duty drill/driver, and is going to struggle with tasks like driving half-inch lag bolts. It will be able to do it, but you'll probably have to gear all the way down, and it won't be nearly as quick as one of the heavyweight drills from many other manufacturers that can provide the necessary torque while keeping a higher average speed.
If you're looking for a premium drill and money is no object, in my opinion you'll be hard-pressed to find a better do-everything drill/driver for wood shop work. For framing, construction and metal work, though, I'd probably suggest looking at the Hilti SF 6H-A22 (percussion drill) and SF 10W-A (heavy-duty drill), which have fine engineering and attention to detail like the Festool but are geared to deliver much higher torque under load.