BTW contacted support about upgrading from 9.1 to 10, was advised the upgrade tech fee would apply even though I believe AC has to do it to credential the machine/database. I am somewhat confused thought if credentialing required it came under the basic yearly support fee and not the add-on fee.
Awaiting confirmation again from support who thinks it should work 9.1 to 10.0.1 without difficulty however been there done that didn't work.