This evening I decided to tackle an issue that has been starting me in the face for years: the right rear spring was not seated properly in the bottom plate, and the left rear spring had its rubber pads mounted in reverse (meaning the top rubber was on the bottom and vice-versa). Not good obviously, but I dreaded the job.
It turned out not so bad - it took a lot of time, but I was able to correct both ailments in about 3 hours' time; I should mention I had Monroe spring compressors without which I would not have been able to do it. Plus there is a sequence one has to go through in compressing and loosening the springs, by using a hydraulic jack in creative ways, in order to be able to get the springs out or turn them as needed. One tip: be very careful not to let the axle drop so low as to damage the brake hose(s). And I had to undo the top nut on the shock absorbers as well, and getting them back in place takes some finessing.
The point of all of this (which probably does not make very much sense - until you have at it ourself) being that if you would want to change the rear springs, it is a job that can be done fairly easily by yourself so long as you have a set of good spring compressors (about $60 at an auto supplies store near you) and are willing to fidget around with the springs, raising and lowering the axle at various stages of the process.
Actually if you do plan to replace the springs, replacing the rear brake hoses (not a bad idea if you don't know how old they actually are, since they constrict with age, unnoticeable from the outside - and they are quite inexpensive items) at the same time would be a good idea, since not having to worry about these hoses would make the spring job that much easier.