I bought this recently to upgrade from my 03 all metal Record one, since after a while rust eventually appears around the stamped holes in the back plate where the plating cant quite cover fully. I also wanted a lighter front derailleur that would be a better match to the new carbon crank as well.
I found that after fitting it up, the front portion of the cage was really close to the 53 chainrings teeth while there was a very huge gap at the rear of the 53 chainring, a quick glance back at the old derailleur and it was easy to see why the new carbon one had this big difference.
The carbon outer cage is a bit too tall at its frontal portion by the plastic guide, and because of this there is a space of 2mm below the plastic guide, while the old metal one has the guide flush to the bottom. In case you are wondering, both plastic guides are the same and fit right up to the top of the outer cages.
To correct this issue i carefully used a Dremel moto tool to reshape the curve of the carbon cage so that i got it flush to the plastic guide at the front and then tapered it back off gradually,just like the arc on the older metal one.
Shifting is now much cleaner since the chain is fully on the guide when going to the small chain ring,whereas before it was twisting on an angle as the plastic guides lower area is tapered a bit.
One thing quickly apparant is that with this carbon unit its now possible to get the full sweep of the rear cluster without having to fine tune the derailleur (aka one click more out as you go past the 16 cog if not it rubs slightly scenario). This is not a technical job but you must have steady hands and patience, if not you will ruin the carbon cage easily. It might be best to use a highlighter to draw the new arced line on the cage before you reshape it.