There are some interesting viewpoints here. The particular dealer I talked to was wests cambridge which I was advised to use by Steve. I can only assume therefore that they know their stuff on renaultsports
TDF said the pulleys are often cracked at 5 years, suggesting they will eventually fail. Then I got a quote from KTEC and they also recommended changing it.
The TB does indeed say it needs changing... Renault repair manuals have been saying that since they started fitting the dampened pulleys back in '03 on the vvc'd K4M's and the '225 is the same.