Are you certain? Most of the "keystone" jacks I've seen look significantly larger than Leviton's quickport stuff ... granted, I've never actually tried to stick a standard keystone jack in a Levition decora quickport frame; they seem so much larger that I'd always just assumed they were different.

Is it possible the OnQ/Legrand stuff is not the standard "keystone" form-factor, and made to be Leviton-compatible?