Looking to buy a high cut ballistic helmet and head is exactly 23" in circumference. Most show a medium up to 23.5". Should i get a large or stay with a medium?

Helmet sizing is highly dependent on the pads, not only the pads thickness but their compression. A medium should fit you fine depending on the pads.
Back face deformation is a reason some people may choose to wear a larger helmet than needed. Using thicker pads or pads with little compression in a larger helmet keeps your head further away from the helmet shell in case it's bulged inward. Hard pads that don't compress can make wearing a helmet suck though.
Using a larger size helmet has disadvantages also. 'Larger helmets weigh more' and are obviously bigger.

Thank you for the explanation

If you're on the fence about what size helmet you should get, get the larger size. Whatever helmet you get, buy 4D Tactical Zero G pads for it. Bar none the best thing out there. We of Arfcom don't call them "tactical booby pads" for nothing.