The McDSP Analog Channel LE 3.1 was easy to install and I had no compatibility issues with my computer. I bought this plug-in as part of the Project Studio LE bundle and it was delivered electronically to my iLok. Within minutes I had the whole bundle installed and the plug-ins up and running. The interface of the plug-in is straightforward and is easy to follow. Since I bought this over the internet, I didn't get a manual, but the plug-in is easy enough to use that I never had a need for a manual anyway.
I am running McDSP Analog Channel on a Mac Book Pro laptop that has a 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM. I am running it with Pro Tools LE 7.4 that runs off of a Digi 002R audio interface. With this configuration, I am able to run a high number of these at once if I'd like. I have used up to five at once and I don't think it would slow your system down to use more than that. This being said, it really depends on how fast your computer is when it comes to running plug-ins on LE systems.
I've been using the McDSP Analog Channel LE 3.1 for about six months and I have found it to be a great tool to quickly fatten up a track. It adds a bit of warmth and sounds great on electric guitar, electric piano, and vocals. Since I got this with the McDSP Project Studio LE bundle, it was really cheap and was a great deal. In fact, I would recommend the whole bundle as McDSP makes some great plug-ins and they offer a great deal with their bundles. This plug-in has a great sound quality and extremely easy to use and easy to get a real quick from. I wholeheartedly recommend the McDSP Analog Channel and all of McDSP's plug-ins.