I like the idea, but not in the signature - it makes for very long titles. But the estate names should be more visible, I agree.
The long title shouldn't be an issue because he was speaking about adding it to Knights titles only. In a few cases, where they are marshal, ambassador, and/or realm council member it will be long, but in many cases those who have those positions also are lords and this addition of the estate is for knights only, could even be knights who hold no other position so you don't need to worry about the long signature.
