Hi Matt,
I'm not really sure what information you are looking for...
I have owned and restored both a Series 3 Lightweight and a M151A2. I sold the Lightweight a few years ago, but still have a few Land Rovers. One reason for selling it was that it spent most of it's time sitting in the garage, it was not as useful as the 110s as I couldn't get as much stuff in the back. The M151 spends just as much time sat in the garage, but it is at least a bit different when I take it out and about.
Both suffer from rust, but the Lightweight is easier to fix as you can get the chassis sections and repair it fairly easily. The M151 requires a lot more effort to fix and mine had to have new floors etc. In the UK at least Land Rover parts are cheap and easy to obtain, restoring the M151 over here cost me a small fortune in shipping and import duty alone.
Over your side of the pond the opposite will no doubt apply!
Chris