i've used versions 3.x through 4.22 over the years, and on the audio side of processing, there didnt really seem to be any major differences at all. 4.22 has a major upgrade with the mixer section, in which they added vst capabitlies and a better " console " look and feel with the mixer windows, but the audio menus all work and look about the same. you still have to open an external audio editing program if you want to do any major splicing, and it does offer the same time stretch/pitch shifting tools that it did in 3.x versions, same eq that's available, and a few other options. it basically works exactly the same as it did on the earlier versions exept for the plug in's capabilities. the midi section is a little different now. i cant imagine that 4.5 would be much different than 4.22, which, like i think (or remember) that audio-wise it isnt too much different than my earlier 3.? versions. (i cant remember exactly what version) . i may have an earlier 3.? manual laying around, may take a while to find. by the way, where did you find the 4.5 manual, that would be helpful.