one might queestion that dealer's reply/motive... but - from all the reports I've seen - and having put a set of Gators under a CC deck - results are usually positive.
Much depends on what you want the blades to do. They do a better job of chopping up cut grass clippings and will usually improve your deck's discharging. Overall, they are a longlasting blade unless you are cutting on very sandy soil - the sand will wear the blades fast.... as any blade. They don't seem to improve cutting in a mulching mode with plug much.
Just be careful that you get a true match for your particular deck - Gator doesn't make their type of blades for every single different deck out there... and they also make several blade versions.