The diesels weren't sold new in California, they couldn't meet the CARB emissions regulations. That's why there are so few in otherwise MB-infested SoCal. Interestingly, there seems to be an active market importing used examples. When I sold my 1998 this past spring, it moved half way across the country to the bay area.
I gave up after 5+ years and 55K miles. I had very few problems with the 210 chassis stuff, it was all the engine and drivetrain. The final straw was when a burnt out glowplug broke off in the head while being removed. The car spent three weeks in the shop while a very good mechanic teased the remnants of the plug out using dental tools. Including that little incident, my car spent 11 weeks in the shop for repair (as opposed to scheduled maintenance) during 5 years of ownership. As much as I like the E300 turbo, I sold it.
On the plus side, it retained it's value very well, and the overall cost of ownership was quite reasonable. I purchased an exceptionally clean 1993 300E with about half the proceeds and invested the rest into a rising market. Everything works out in the end.