Once you have a "TE" you wont go back! Give it a subtle sport-conditioning: bigger tires, tasteful sport wheels, mild tinting, about an 1" lower and you'll not only have an eye catcher, but a fun ride that's got all kinds of utility for an active life-style.
At around $12,000 insist that everything should look good and be in good working order both in and out, as well as, mechanically. Good and straight ones are hard to find.
As for your concern, more than the self-leveling, I'd stay away from the 4matic. I've been told that unless you get one that's less than 3 years old and even then, one that's been on a good, documented maintenance schedule, be prepared to spend money. Mine came with a complete service file from Stead Motors in Walnut Creek from the day it was delivered in '88. My self-leveling in still going strong, with 166k on it. Not even a hint of trouble. I expect that with normal maintenance, I will get way past 200k. When it finaly does quit, and if I don't decide to repair the self-leveling, I've been told that switching to a coventional suspension is not a big deal. I don't believe that the rear springs will work for the TE. It's a different part for even a 300E vs. TE.
As for the speakers, I've been quite satisfied with the stock system and Becker radio. Then again, I drive with the sun roof open as often as possible, even at night (I used to be an MG-driver), so perfect sound quality is not a priority for me. Of course, it's because the car is still relatively quiet, for having the sun roof open, that I keep it open so much.
Here is a link to the Mercedes-Benz Club of America website that talks about "When Do Parts Wear Out?": (if I didn't list it properly, you can find the article on their website- you don't have to be a member to access it.)
I'm in Concord. Let me know when you get one.