My new (to me) Mercury EFI 175 will not have an hour meter.
I'm considering installing one of the "induction" type meters.
Anyone have any feedback on them?

Sorry no feedback but I’m curious as to why you wound need a meter? I run the same engine (2001) and have no need to know the hours. I keep recommended oil (quicksilver) in it, good gas (non ethanol), Mercury quick clean twice a year, and change the plugs and lower oil yearly. Just regularly maintenance should have no major issues.

I installed one after I rebuilt my pro v 150. Works like it should. Just wrap inductance wire around one of the plug wires. Good way to keep track of maintenance intervals, and it could help in the event you decide to sell it.

You may want to look at the Mercury Vessel View Mobile depending on the year of your motor. This will work on just about any Mercury Motor built since 2004. If it’s a Smartcraft compatible motor, this will work. It will give you the actual hours on the motor since it was new because that info is stored in the computers memory. It will display any information that a Smartcraft gauge will display. I have Smartcraft gauges and I also have this module. I works perfectly and it lets me have more info displayed at one time. I have seen new ones ebay for $175.
https://www.mercurymarine.com/en/us/gauges-and-controls/gauges-displays/vesselview-mobile/

Itll work