Thanks for the reply Jack. Like I said, I just had the seals done and haven't driven the car much since, but it appears the problem may not have gotten any better. I'm going to keep monitoring it for a while and might even try a different oil, so we'll see. I would be happy with one quart in 1500-1800 miles for another 50,000 or so before needing a valve job, but I'm not too excited about doing one right now with only 85,000 on the clock.
I assume that if my guides are bad, that means a whole valve job, or at least that's what I've heard. What can I expect to pay in U.S. $? This is my first MB and I really love driving it, but I paid a premium price for it and have already put about $1000 into it. I'm just a poor government employee and depend on the car as my everyday driver. Things are adding up!