With 10% of rents I'm saving, it gives me a margin for error to not have to penny pinch my plumbers and handymen.  

This of course is after decades of penny pinching.  

Keeps us in shape too.In my experience I've found that focusing on the big expenses and not caring so much about pinching pennies everywhere else is more effective.

Pinch: an app that enables you to post 24 months of previous rental history to all 3 credit bureaus and continues to post your monthly payments for free.

Is this pinch on inventory sort of forcing appreciation by supply/demand economics?

So might be good for some in a pinch if lenders are not offering right now.  

Renters feeling the pinch may not necessarily share similar investor enthusiasm it seems or do they?

I don't know that much about your specific situation, but when you aren't hyperleveraged you usually have some options available in a pinch.

The refrigerator in one of my rentals is 30 years old, and I know that because I bought it new when I bought my house that I live in now, and it went to the garage when we remodeled the kitchen 15 years ago and then to a rental when I needed a fridge in a pinch 10 years ago.

Some days it can be very, very tough, and other days you just want to "Pinch" yourself because your having so much fun; but it isn't a Passive Investment like you might get with some of the other options you mentioned... but in my biased opinion it's a whole lot better.I hope that helps a little.All the Best!