Hey, no problem. The only way to learn is to have your questions answered. I have been going back in the posts to find most of my questions asked and answered. There are still some questions I can't find answers to but they usually get answered. So now that you know that the 2 ch's though all slightly different still kick a 3 ch in the pants you must be asking yourself what you should do. Regardless of which you choose it will have the basic 2 ch qualities that separated them from the 3 ch. If you like having more channels, having a slightly looser amp and some fizziness then you want to keep what you have. If you want your amp tighter, with less fizz, and to have better tone you know what to do.
In my case, if I want tighter than a Rev G I plug into my Mark IV. If I want good cleans I plug into my Mark IV. If you look at the 2 ch and the Mark IV you'll find that the 2 ch is better suited for heavy rhythms whereas the Mark IV does tighter rhythms better. I would say that the Mark IV has a better soloing tone for the types of stuff I play as well and is more versatile. Some will debate the soloing tone as being better in a Rev C. I think it all depends upon what you are doing with it.
You asked earlier about a 50 cal. If you have a Rec and a Mark IV you will never need a 50 cal. Nitrobattery was feeding you good information. Listen to him. He has been through the gamut.