What is the price on Q16 and M5 per drum? That may help us better chose which to run.
I have been running the 99.9% alcohol may try the M5 this season. I Bracket Race and run the alcohol for the cooling effect & the extra power from it is a plus. I run the Ron's Terminators and they do not milk the oil.
If your presently running M1 or plain methanol IMO it would be hard to justify switching to Q-16 based on the cost of both.
Being your running MFI I would suggest you try some M5 but stick with the methanol.