The Tikka and Zipka plus versions do use PWM and some people can nitice it.
I have only noticed it when other people using it and one or us both are moving heads.
There also was/is a Princeton Tec Aurora lamp which had a flicker every second or so, only very slightly but very annoying when reading a book (no problem when cooking or similar). It kept me from buying one. PT justified it as an energy saving measure, which was a very silly excuse. Does anybody know if this issue is fixed now? Otherwise it would have been superior to the Tikka in almost any way.