I already have this 68W LED bulb from Philips, paid around 70 euros on clearance sale. It's an absolute beast of a bulb.
I have noticed the voltage spec printed on the bulb and this lead me too googling, and I found a guy claiming he accidentally connected this to 220V AC, as the socket is the same. And it blew up inside. Apparently it still has an internal driver of some sort, imitating volt-ampere characteristics of HCI bulb.
It's bit silly to have two drivers in series (ballast is basically a driver), but if that is what it takes to finally solve this issue, I'll take it.
So my questions remain open...