I can get my recurves very quiet, are they as quiet as the quietest longbow? That I don't know. I've had plenty of longbows over the years and didn't notice a lot of difference in the noise level between the longbows I've had and the recurves.
The key with a recurve is to tame the string slap agains the limb. I really like yarn on the string (Bow Hush), but some put mole skin on the limbs. As long as you have something soft where the string touches the limb after the shot (the contact point is longer than you might think) you should be able to make your recurve nice and quiet.
Fur or wool on the string for silencers, proper tuning, heavy arrows, all aid in toning down the noise of the bow. Three under shooting presents a particular challenge and I have never been able to get a bow as quiet shooting three under as I can shooting split.
I will say the quietest bow I think I've had was a 64" Griffin hybrid longbow. It was uncanny, but once it was tuned it was very close to silent. I can get my Blacktails, Silvertip, Dye, and Robertson recurves plenty quiet, but that old Griffin was in a league of it's own.
Stupidly I sold it...