I like 53/52-42-28/26s. I have many times use front derailleurs where the chain dragged on the roller/spacer on the cross bolt. As far as I can tell, that drag causes no issues except rapidly wearing out the roller. My solution has been to get a stack of small washers and use them instead of the usually plastic rollers. It also allows me to easily customize the width of the bottom of the cage. (I like to narrow it down. Improves shifting to and from the small chainring. Yes, I have to trim the FD more, but that isn't hard with DT shifters.)

I did buy a new DA front derailleur 9 years ago building mu my custom to use with a 53-42-28. Even though it is touted for rather different (but still triple) gearing, it works better that anything I have ever used. A tough statement for this non-Shimano guy to have to make. (I did my research. The Ultegra was "right" for the chainrings I was running. But it had a dull brushed finish that would look just wrong on the bike, The DA was bright shiny chrome and looked "right". Amazingly, the good looks actually worked well.)

Edit: I would go with my washers and chain drag over the extensions every time. They strike me as both a place for the chain to hang up and an additional loss of stiffness at the flexiest part of the cage. The bolt across screwed tight with good spacers inside serve to turn the cage into a closed box from an open "U" and improves stiffness and lowers flex when you shift a lot. For engineers - think of the cage as a cantilever truss, one where diagonals cannot be used. The difference between solidly fixing, just pinning or completely removing the far end member will be large.

Ben