MM should work fine on 4s with the usual mods done to it , fan , 25v cap , external bec etc
I will be running the Medusa 36-60 1600kv on 5S in the D8 so for 4s you will want something around 2000kv.

The stock clutchbell is 16t in the kit so i am starting there with a 16t pinion since the rpm on my set up is similar to a nitro motor rpm .
if you go with a 2000kv or near motor and 4s you will also have similar rpm to a nitro motor at around 30, 000 rpm

I'm guessing 16t - 18t pinions will cover most set ups in the D8 .