I already have a Mini-Presidio.
It is one of the limited editions with the checkered handle, the same design that the 'ultra' uses, and the S30V blade. It is a fantastic mid-size folder.
Thats what made me want a large Presidio folder with the same upgrades.
The 520 was a great knife except for the pocket eating handle tread. It was probably the most solid folder BM has ever made.
The Wilkins Grips are rather expensive. However, they are only one way to get a hard use, pocket friendly, S30V, Axis lock folder. Yeah, I know about the Rukus/ Mini-Rukus.
I just sold mine. I never cared for the handles on the Rukus series. They were big knives. Even the mini Rukus was bigger than I like to carry. The 552 Ritter is just about the perfect size for me. It doesnt weigh a ton either. I prefer the Ritter blade shape over the Rukus as well.