I selected the high speed for those low decibel readings on my post and desired airflow. My RV fan switch does not have a high/low setting; I could add a toggle switch and bypass the one built into the fan if I wanted to lower the speed or add a 2 speed switch.
I've used it for the past several days and even cooked the real test: bacon. Plenty of hot air exhausts from the RV from the stove and it seems to be working just fine so far. Still doesn't stop the smoke alarm from going off.
Our current hood is a ventline which is 100 CFM. Upgrading the fan increased it to 171 CFM and less noise. The PC fan is designed to range in speed from 40-171 CFM so it certainly would support being variable with the right controller or perhaps the toggle switch as I mention above for 2 speeds. The lower speed might be wise to run for general air circulation like what many newer homes have. I'm just content for it to be running at high speed and dramatically quieter.
No warranties, expressed or implied.
. I kept tie other fan parts in case it fails and I need to swap it back.