Here are some pics
This is my daily driver, personally I love driving the old slushbox.
Here is my track car and my hauler.
I agree that these cars are one of the most rewarding drives. Somehow when you get into a 16v, that engine growl, the balanced stiffer suspension, something about the high bolster seats, it just encourages bad behavior and then generously rewards it.
I don't think there is any difference between any of the models as far as sorting out things goes. One thing I have found about the old CIS is that it is robust and durable. It is very finicky and there is no OBD to guide you. However, if you removed it all, it would fit in a shoebox so there is not that much to it. Most of my sorting out of CIS has been cleaning electrical contacts to insure accurate signals. In restoring four 16v's I may have replaced two or three sensors and a couple switches across all of them. Again, most of the parts are very durable and once well sorted I have found it to be very reliable.
I have been building out a replacement for my ML55 that I use for towing. It is just a well kept MB serviced example with 120k. I had not previously worked on my original ML but decided to do a lot of the work on this one. By comparison I am convinced that an old w201, well sorted, may be the best driving value out there, because it so cheap to work on.
The properly sort out things on the ML, I needed FOUR catalytic converters, and four o2 sensors, and 16 plugs with wires to their eight coil packs, and on and on. I could completely sort out any w201, throw in a paint job and a vacation for two for the cost involved in just replacing the ML's wear related serviceable parts, shocks, mounts, brakes, fluid changes and the aforementioned.