FWIW I can't remember a dist-upgrade of a samba server in my life where smb.conf changes weren't a very annoying distraction...
It seems that whenever you have anything within the global section of smb.conf, like domain membership or log level or any number of assorted similar settings, it lists that in the diff as something to be removed. It also doesn't seem to like shares commented out, saw a lot of that in the diffs slated for removal, too. And just executing the 3-way merge seems to inevitably lead to the removal of all local settings en masse, and then there's no backup file for them. (This might be a generic ucf thing, which is probably why that option is marked experimental?) Using a .d subdirectory to farm out settings into more manageable hunks isn't really a hack these days, it's SOP to avoid having sysadmins go berserk when doing upgrades. -- 2. That which causes joy or happiness.