I realize this answer is likely too late, but I don't know that "my characters and digital items will be seamlessly picked up" is true. Only someone at ZOS would be able to give you a hard yes or no on whether or not they're willing to transfer your stuff to a different account, but as far as I know you're talking about a totally different account. I purchased ESO directly as a second copy to my Steam version when it was on sale, and they are not automatically linked; indeed you cannot log in at all on the regular client with your Steam-created account (unless you've bought the game a long long time ago, before certain integrations were made).

Contact customer service and be sure to explicitly ask if they can do what you want before making the decision, if it's not too late. Good luck!