I have used both Amsoil 100:1 and Belray MC-1
I used the Amsoil at 100:1 and the Belray at 70:1
The amsoil has hard black carbon deposits that are difficult to remove.
I soaked the engine in automotive engine flush and the pieces would come out in chunks when the engine was started. No clean up was necessary.

I have been useing the Belray at 70:1 for some time. The MFG says it is good to 80:1 so that is why I chose 70:1. It burns clean and also leaves the engine and exhaust covered in balck carbon deposits. These are soft and can be wiped off with a rag and some thinner. Soaking the engine in automotive engine flush reduces or removes most of the carbon deposits and makes everything easier to clean. Just using a cloth takes care of most deposits.

The bugman report can be found here.
http://www.rcaircraft.net/articles/oil_test/