I think the article is great and the methodology is well documented. However, I don't like linked servers, openrowset, opendatasource. I feel they are a security risk, bugy to manage over changes/migrations, and incur unnecessary overhead. I am not sharing this to poopoo your solution, because I understand that mine is more a matter of preference that in reality is subject to details about the environment and philosophy of a particular company.
I have created a tool that does essentially the same thing as yours, except that it uses a browser front end. It actually stores the metadata much like yours does so that it can populate the drop down list to select which servers to submit the query to. Further, their is a database box to select which database to submit the query to on all the servers that were selected. It seems the tools accomplish roughly the same thing, except that my solution allows any sql to be submitted including DML, which is nifty if I want to submit an updated version of a stored proc on all my DBM databases. Also, mine just makes a connection VIA oledb w/ integrated security versus using linked server technology.