Been around machine shops all my life. We usually have scroll or rotary vane models. Although I've seen some IRand duds, we have one at current job that just got rebuilt with a tad over 55,000 hours. the rebuilt scroll alone was over $7000 installed. This is a 30 hp model. Run it at 125 psi.
My all time favorite is Kaeser. We had 2, 25 hp models at one shop, each with over 25,000 hours and almost never had any problems.
Another favorite is Hydrovane. Although these run at a lower 105 psi setting. I think we had 32,000 hours on the one we bought used at an auction.
Quincy builds good stuff as well as others. You just have to ante up to get into this arena. It all can be worked out into a cost per cfm at your needed psi dollar figure. If you don't need much air, you don't need one of these.
PS, I come home to a small little "buzz" model that annoys the H outta me.:laughing:
I have an oldie but goodie 5hp 3 phase speedaire but no 3 phase here at the house.