I went through so much trouble trying to get the first layer to stick, it was a nightmare. Every time I'd solve it and fix the problem it would work for a while and then start to come unstuck again. There's just so many variables that come into play - different ambient temps, different filaments etc etc. The ultrabase solved most of my problems and like you I found a lower first layer helps too.

I don't use mine much now, I was inhaling a lot of plastic fumes and even though I had it set up in a spare room with an octoprint (best thing I ever got for the printer) I was still smelling and tasting the plastic for up to a week after printing. They say PLA is harmless and it's not an offensive smell but I'm not convinced that it's as harmless as they make out. I'm in the process of building an enclosure for mine so I can print some higher temp materials which I'll do in the shed so there's no fumes in the house.