It's hard to improve on the performance of a T-square fence, but I think I've done it. I got frustrated with clamping on an additional subfence every time I wanted to make a rabbet with a dado set (where part of the blade is actually housed in the fence), so I made a new set of fence faces with interchangeable inserts. One insert has a cutout for rabbeting; the other is plain for ripping. When the arc in the rabbeting insert becomes too large, I just install a new insert.
To maintain the usefulness of the fence's scale and cursor, I removed the original 1/2-in.-thick faces and replaced them. I made the new faces from 1/2-in. MDF and mitered the ends at 45 degrees. The original faces were glued to the fence; I attached the new faces with self-tapping hex-head screws. The inserts don't need to be screwed because they slide firmly in place.