I think LXDE is like a baby KDE but a full DE nonetheless.
Whereas Xfce is like a baby Gnome but a full DE nonetheless.
A properly working Mandriva system, which is what PCL is
has to be one of the top three systems available, and my
LXDE works, oh, about 99%. A couple of softwares are
still troubling. Nothing fatal just a library here and there
not really connected to the LXDE desktop itself.
But, that could change in an instant, and 100% everything,
as in the past, would be remarkable.
Efficient and logical, then yeah, LXDE is the lightest.