My setup is as follows:
campy ergo, ultegra rear, jtek, shimano hub/cassette 10 speed.

I just bought a campy wheelset/cassette with the intent that I'll be replacing my ultegra rear derailleur with a campy rear derailleur in the future.

In the meantime, I plan on using the ultegra rear d with the campy wheelset/cassette and ergos. Because the upper jockey shimano rear derailleurs float, should this still work?

Has anyone tried this out?

If you already have the correct Jtek to mate 10s ergo with 10s shimano then yes. Otherwise no.

Floating upper pulley will not make an incompatible drivetrain system, compatible. As in your case.

..thats the problem. I don't have the proper jtek. In fact, I don't think jtek makes ergo/shimano derailleur/campy cassette shiftmate.

Anyway, just thought I could make that transition...

This article might help. It's interesting, anyway. Check out the Hubbub Shimano modification.

If I read this right, your Campy 10s cassette has a pitch of 4.15 mm and the Campy 10c Ergo levers move the cable 2.8 mm for each click. The Campy 10s derailleur has a shift ratio of 1.5 and the Shimano rear Dearilleur has a shift ratio of 1.7. The Hubbub modification will reduce the Shimano shift ratio to 1.6. That might be close enough.

Which shift mate do you have. You might be able to swap the pulley.

The Jtek might work. I know they don't list your specific combo so try it and see. Otherwise depending on what RD you wanted they aren't that expensive. I picked up my centaur's new for less than $70 each. Now if you want carbon, then I understand your wanting to wait .

where did you find a centaur for $70? All i could find was 90+. I'm after the alloy ones.

Carbon for under $100 https://www.ribblecycles.co.uk/sp/roa...ar/CAMPGRRR730