To my knowledge, the store format is the same so you should be able to lift & shift the store to a new server
FormsPublisher hasn't changed (noticeably) since 6.5. There should be no problem with your upgrade unless you've made some customizations to your DCTs that rely on JavaScript DOM hacks or similar things that circumvent the API published by IWOV.Expanding on your question, the bigger story is migrating your content store. To my knowledge, the store format is the same so you should be able to lift & shift the store to a new server (or patch directly on top of your server, but I wouldn't recommend that without testing it elsewhere and/or backing up your install and store) -- but I haven't explicitly migrated a 6.5 store to 7.2 myself yet.