Campagnolo 9 speed vs 10 Speed
 

If I have a 10v cassette and a 10V Ergo, Can I simply replace the 9v equivalent and be done?
The rd is a Racing T, RD01-RA309. I assume it will work with 10 speed cassette..

Your Racing-T is likely the last iteration of the 9-speed units, with the with the new bulbous lower pivot and adjustable lower pivot tension ring. If so, then it has the new 1.50:1 actuation ratio, and therefore is 10-speed compatible.

A pic would confirm.

@Dave Mayer - I confirmed after the post. It is the last version.
Currently working with a 9V cassette and 9v ring in the 10V Ergo (second gen Ergo of course).
I am thinking of converting to 10V to add a lower tooth count as an option. I run out of cadence too soon going down hills. The 53/11 on the De Rosa is a bit much but a combo of 52/12 would be better than the current 52/13. All this on a triple 52/42/30.

Loosing the 30/26 to a 30/25 would be acceptable