What is a "cave cut"? Just smaller than regular cold water suit? Caves are normally ~ 70f?OK, I think I'd be sure to get a few more dives in it with thickest undies you're ever going to be using. When it comes to cold, my mantra is that if you can stuff more undies in to the suit, then you should.
I guess my other point that I was reluctant to mention, but my guess is that your asking price maya not get a lot of action. Someone willing to pay $3K for a suit is going to want a warranty, minimum. You might look into the transfering of your warranty, as that could be a "thing" for a buyer.
I'd hate to see you take $1000 hit only to get a new suit that's fractionally smaller.
As an aside, is this a custom suit? If so, who measured you? Do they have any responsibility in this? I know SANTI allows for you be wearing 400 weight underwear in theis size charts. The measuring may not be the problem. It may be the lack of 400 gsm stuff. My recollection is that you need to advise SANTI that you want a cave cut, as you do with DUI.
I know with Seaskin you have to specify if you're using it for cold water and thick undies... they pad it out some