I can't speak too much about the installation process with the Digidesign Solid TDM virtual synth, because the one that I have used was already installed on the system. However, since I have been using it I haven't encountered any problems relating to installation or compatibility and haven't heard about any issues whatsoever really. The interface of the software isn't hard to follow, but it does offer a lot of different parameters and sections, so it will take a bit to get used to everything going on. I don't think that a manual is necessary for this software unless you are a beginner with virtual synths.
I have been running the Digidesign Solid TDM on a Pro Tools HD system that runs with a Digidesign 192 I/O and an Apple G5 computer. This is the only set up that I have experience with the software, but I can say that on this system it has run quite well and without issues. I can't say how well an RTAS version of this software would work with, but as long as you have the proper system to run your sequencer on, I think that you'll be in good shape and Digidesign software usually runs pretty well.
Overall, the Digidesign Solid TDM is a very nice sounding virtual synth. It provides a ton of options that make it possible to get all sorts of synth sounds. The presets are pretty cool and of course you can make and save your own as well. I can't say that I have any real complaints about the Digidesign Solid TDM as it is an easy to use synth that sounds great. It isn't all that expensive and is definitely a synth that should at least be tried out if you are looking to add virtual synth to your set up.