It's true, a backup can be made from older v100 in this case, and restored using the v110 gui on another router.
No conflicts, no errors, dual SSID, multiple dhcp servers, fixed dhcp, spamhaus and countryblocking, all of it just works !!
I had a hell of a time until now, always a fresh rebuild, 2 hours minimum.
Thanks to all the Tomato programmers, especially Shibby, you guys are awesome.