I have used them before, they can take a fair amount of juice as there is a lot of mm2 area, seeing as telly lopty's run at nearly 16kc they are ferrite, if you find a telly with an iron core put it back in and put it on ebay it'll be a valuable vintage set.
I've found a couple of ferrite loptys with air gaps.
You can light a cfl or fluo with a loptys secondary, google royer flyback driver, you only need to wind 8 turns or so on the backside of the lopty, I htink you can even light a cfl from a 1.5v batt.