KevskiFor what it's worth I've got the regular full weight K108s with shifts as my 50/50 ski and my legs haven't fallen off or anything like that yet. If you're just getting into backcountry and not sure how much of it you'll be doing (like I was when I bought that setup) I imagine you'll probably be happiest with regular or 50/50 on custom. Tour cores seem like a pretty intentional move if you're not certain you'll be doing longer tours.
But second to shooting an email to ON3P about it. Also worth a listen to the gear:30 podcast first - Scott breaks down the core options pretty well in that episode.
yeah i definitely could just go with the regular layup
just don’t know what the downsides are to the other layups
ill definitely hit them up sounds like they communicate pretty well