I have my AR6s mounted at true centre and I love them. I had a little bit of trouble in deep snow but to be honest it really wasn't as bad as I thought it would be. They still carve on groomers really well and being mounted at centre makes it so easy to do butters. Just for fun I'm always buttering around to switch rather than jumping now.
If they're your only skis then maybe go for 2.5cm back from true centre, but I'll happy say that I'm very happy with mine at centre.