The main rules have been in my "to read" pile for a couple of months. I've read the introduction and looked at the pictures, but haven't actually got any further
The solo rules are in my "to download" list, but I keep forgetting them, so sadly, I don't know. I had assumed they were just a thin shim over the main rules, but by the sounds of what you're saying, they may be more substantial.
I've put them in my weekend to do list (along with tidying away Christmas decorations), so there is a small chance I may remember this time