Questions about upgrading from to metal from plastic Male Chastity Now Amicus

Just wondering anybody had any advice about switching from plastic (Holy Trainer v2). Mainly are there concerns about sizing with metalthat are different than plastic. I seem to remember reading something about metal devices should be a little bit smaller (or bigger) than plastic counterparts?

Also does anybody have any experience with the device itself?

Thanks so much. I'm excited for a real cage!