Dp makes a nice difference in sound quality even with the stock catback. I did a 3 inch 42 draft designs catted nonresonated dp before I got a catback. It sounded meaner than stock, especially when I got on it, but a little too quiet driving gently. I added their catback to get a ful turboback setup, 3 inches stem to stern, and now it is loud as shit...too loud, in fact.
Don't get a louder catback until you add a dp to your existing setup. You might find it's perfect at that point, or even too loud.
Your exhaust is going to be relatively quiet if it has a stock section, be it the dp or the catback, since a big part of the volume comes from having an unrestricted 3 inch setup from the engine to the tailpipe. Add the narrower, more restrictive downpipe or the stock catback to an aftermarket section, and the noise level is going to be limited by the lack of flow and the greater muffling of the factory section. As soon as you open up that sewer pipe all the way you'll hear a shit-ton more noise.
If you go to a different catback first, and then decide a few months later to add a dp to the equation, you might end up having the car be way louder than expected, and it'll be a lot harder to switch directions and go quieter. Plus, you'll feel a bit of power over Stage 1 by adding a dp. An additional benefit is that if you flash to Stage 2, your sound quality will get even beefier with the more aggressive mapping.
Before you jump the gun, remember that it's easier to make a car get louder, but not so easy to make a car quieter once you take a look at your choices. If you do get a new catback added. there's a good chance it'll sound like mine: ridiculously loud.
http://www.golfmkv.com/forums/showthread.php?t=178771&page=3
I wouldn't worry about clutch issues. Mine lasted to about 108k miles and I was tuned since about 25K or so.