OK, I will stand corrected from my statement that all 9sp Ergo works with any 9sp RDs.
However, I owned a 1999 Marin Vicenzo with Veloce 9 (pointy hoods) and in 2002 replaced the Veloce RD with a new Racing Triple 9sp RD (and a bigger cassette) and had no issues. The bike is long gone so I have no proof of my claim.
Apologies for any mis-information.
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Vintage, modern, e-road. It is a big cycling universe.