Does anyone use them? Are they more problematic than butyl tubes, other than losing more air?

IIRC certain kinds of repair patches don't work too well: whilst they adhere fine, they can't deform/stretch anything like the latex tube can.

I've heard you can get latex-specific repair patches/kits, although I'm yet to find them!

Yes.

No.

Do they roll noticeably better then?

I tried them a while ago, they lost quite a lot of air but when they punctured, they tore big slits rather than small holes. Often unrepairable.

found one in the drawer, tried it, punctured with a bang and a big slit, chucked it in the bin.

Tubes = pointless.
Latex tubes = even more pointless. 😉