The Cree bulbs - at least the ones in Home Depot in Canada - actually do have a warning about using in enclosed fixtures. It says (to my recollection) "Do not use in enclosed fixtures with other types of bulbs". So my take on this is that they are supposed to be OK providing you don't mix the Cree LEDs with CFLs or incandescents in the same fixture.
I am trying them out in some enclosed fixtures, too early to tell how that will work out.
I am trying them out in some enclosed fixtures, too early to tell how that will work out.