I'm still using my old style Campy friction downtube shifters (the kind with the dots around the edges).
Shimano Ultegra 6500 RD
Shimano 9spd Cassette.

I am essentially using 100% of the shift lever range, from 100% forward to 100% back, and don't think I could squeeze out much more cable. I do have some troubles dropping down into the smallest sprocket as it is.

Anyway, I find the shifting for the 9S is very good. In fact, I think it is easier to shift 9s than 5s. In particular, there is always a cog where one needs it, so I never "grind" on the back. Depending on the derailleur there is some flex in the jockey wheels to help with finding the gears.

Looking at the shift ratio tables:
Bicycles/Maintenance and Repair/Gear-changing Dimensions - Wikibooks, open books for an open world
The shift ratio on the standard Shimano is 1.7, and the old Dura Ace (8 spd?) is 1.9. Campy is 1.4 or 1.5.

I think what that means is that if I was using a Campy shifter and a Campy RD, I would run out of shifter range, and not get the whole range of shifting.

I think the Shimano 9 spd is also narrower than the Campy 9 spd, to also aid with shifter range.

The bottom line is that I'm very happy with the 9spd using my old campy friction shifters.
I assume 10 spd would also shift fine, if I have enough dynamic range.
11 spd would require something creative like the Jtech Shiftmate to increase the range of pull from the levers.
Using a Campy RD may also require the Shiftmate.

I have not experience with your specific config. I'm not sure why companies need so many "new" derailleurs. Perhaps you'd have to grind down the stops on your derailleur or something.