Yep I have been having a similar conversation with a lad who comes out with us and is building his kit he wants the best weight to warmth ratio and centre zip I have tried to persuade him he can save a lot of money by compromising on one of these Personally I have a military synthetic with centre zip and a down bag with side zip;I always use a bivvy bag as well; all in cost less than half the price of the Carinthia bag I suppose its horses for courses but I think down bag with a centre zip you are going to have to part with a substantial amount of cash.I don't think the advantages of a centre zip offset this for me.Hope you find something though