Yet another rotary screw air compressor thread

Ok, yet another rotary screw air compressor thread. I have read thru some of them. I am going to figure out my usage with a flow meter soon, and make a judgment on how much I need now and in the next few years. My shop is full so I don’t expect to add anything other than more people. I run convertors in the shop so a single phase rotary screw is my plan. I’m expecting to buy something around 20-40 feet a minute (7-10hp). And I’m very tempted to buy the variable speed model. I’m nervous to buy a used model so I think I’m just intending to go new.

A basic 10hp on eBay is $4500

Eaton Compressor 10 HP Single Phase Rotary Screw Air Compressor | eBay

I was told every thing on the Eaton for the 7-10hp is the same other than the motor. The compressor is the same size, so they are just spinning it faster to get more volume.

To change it to variable displacement was verbally at an additional $2000. $1400 for their air dryer. I’m half tempted to leave the current piston compressor directly into the air system to use its 80 gallon tank, and it for a back up, so a tank won’t be necessary.

I have pretty much ruled out IR models. Kaeser seems to be a popular name around here. I have been looking at Eatons via eBay.
I’m asking for:
-tidbits of advice
-brand recommendation
-any first hand knowledge of dealing with Eaton, their talk is good, but do they back it up?
-???? This is my first time having a first hand experience with a rotary screw compressor.

Thanks in advance,
Rosie