Sharkscope will be your friend
I sharkscoped some regs that play these and some have 20% ROI over several thousand games at the $5s, some (decent) regs have about 10%, so it depends what the actual skill is in comparison. I feel there are some really good regs playing these (MTT regs as well as MTSNG regs) but still the overall population in them is pretty soft.
As for the difference between $5s and $11s, I haven't seen a $11 reg having similar ROI (close to 20%) over reasonable sample, but I could be wrong.