I have the second generation H2O with the ComfortLight Pro. I find it works best when I am reading during the transition - then I simply don't notice it cutting in. But when I go to bed late and turn on what is already an orange* screen it can be a bit disconcerting. Overall I have been surprised how little I mind the orange once I give my eyes a chance to adapt ... and maybe it helps with getting to sleep or maybe it doesn't, can't say I've really noticed either way. I have enough trouble sleeping that I leave the warm light setting on and hope at least the placebo effect will help me out.
* My Kobo doesn't just go "warm", in the dark it goes quite a deep orange. You can change your bed time but I'm not that consistent and my chosen setting is far too optimistic.