One obvious con of pump+meth: What if meth injection fail right in the middle of the pull? Just those split seconds of knock can be devastating.
E85 will never fail like that. If injectors get dirty/gummed up, it will be slow and gradually, you will feel the difference.
E85 is magical. It burns so much cooler. It is cheap, smells better than gas too

I was able to get away with 23* of timing with 11.5-12.0 AFR's with stock SMIC, heatsoaking through the gears in 90*F day. NO KNOCK.