Peter,
Welcome to the list. I don't consider myself really a Pagoda expert, as I've only had my 230SL for about 4 years (2 since restoration). However, I am also in the southern California area and I do have some opinions on your questions.
1) The Pagodas are reliable. Some owners complain of an overheating problem, but I've never experienced it.
2) The Pagodas handle well, although the swing axle introduces some quirks.
3) Comfortable, yes. Quiet, decidedly not. Both motor and wind noise are loud.
4) Unless you're going to race or drive for long stretches at Autobahn speeds, I would doubt that the extra main bearings in the later models constitute much of an advantage. Many people prefer the rear disk brakes of the later models, but my 230SL brakes are great!
5) Pagodas are simple enough to work on yourself, although small hands do help for under-dash work. Also, in some respects these cars were apparently never meant to be taken apart -- the heater core and the hardtop chrome come to mind.
6) They do rust -- important to check the critical places when you're looking for one to buy.
7) For a condition 2 car in SoCal, I think you'd be lucky to find one for $30K. For condition 3, needing only moderate work to make it reliable, etc., you might possibly find one for $20K. 230SL's are cheaper than the other two models, and IMO are just as desirable. I also believe that any Pagoda in good condition is a good investment.
My 230SL is manual, and IMO the transmission feels a bit old fashioned -- relatively long shift throw, rather loud, etc. Except for that, I don't know of any specific problems.
9) Mine is European, and I like the look of the headlights and the lack of bumper guards in particular.
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If I may ask, why are you interested in a Pagoda in particular? The main reasons I love my car are its beauty (one of the all time great designs), the overall elegance of the car (leather/paint dash, great chrome accents), and the combination of a roadster/coupe/softop in one car.
But you did mention quiet as desirable, and while it may be heresy to say so on this list, you might also think about a '72-'74 BMW 3.0CS or CSi. (I own one of these too). It's also one of the most beautiful cars ever designed, and has a much more modern suspension and handles much better than the Pagoda, is much quieter, and generally has a much more modern feel. Reliability, rust, etc., are much the same for the two cars. And the price of the BMW is probably only a bit more than half the price of a Pagoda in similar condition. Of course, if you want an open car, the BMW doesn't qualify. It all depends on what you want.
Good luck,
Chris Earnest
'65 230SL