I've owed a few different planes, from a 150 all the way up to a Navajo Panther, and now back to a 1980 H. They are all good, but when I got to a point where I didn't care (within reason
how much it cost to buy, own or operate, I decided that the 337H (non pressurized, non-turbo (but booted) was the best plane on the planet.
I would not fly in a Cirrus, nor will my wife. I don't want to lible the aircraft in any way, but I believe a certain aviation writer who had something to do with radio navigation
alluded to the fact that the Cirrus has the worst safety record of any aircraft ever produced. Of course there are all sorts of arguments as to why, like it is bought oftentimes by low hour pilots who get behind it's speed curve, etc..
But back to the skymaster, I will make one observation about the year because I have owned both a 1970, and now a 1980. The one significant difference (other than the door) is the fuel system. My 1980 has all fuel tanks (per wing) hooked together in a line with one large lower hose. This vs the 1970 which had seperate main and aux fuel tanks and associated mult-position selector, no pump on the aux, etc..
There is some evidence that if you took out 337 accidents that are fuel related accidents(ie.. planes that crashed with fuel in the tanks, but due to vapor lock and selector valve problems) as well as just plain old running out, that it is one of, if not the safest aricraft ever produced. In fact I often wondered why no one ever produced an STC to convert the tanks to a one fill/flow system on the old airplanes. I guess because if it doesn't happen to you, it isn't worth the expense.
As for turbo's, my Panther had them, and they were cool to get you high fast, but other than that (for east coast flying) they are a total waste of time, money, maintenance and heat.
If you want to talk about this in greated detail, just email me direct.
Good luck with whatever you get.