The Tur and others call eating achilas aray in the sukkah a chumra not a hiddur.
Two people can do the exact same thing, one might do it as a chumra, the other might do it as a hiddur.
I doubt anyone would say that Lubavitchers are
machmir not to sleep in the Sukkah, but Lubavitchers are definitely
mehader not to sleep in the Sukkah!