I just received my board, and though I haven't tested it, the other poster earlier said that polarity should be Positive on the Farthest circle from the Resistor. Basically, if you are looking at the Front of the PCB, it would mean Pos is Left, as when you flip it over, the resistors are on the Left, so pos is Right on the reverse side of board. I'm assuming this is the same for the other LEDs as well.
I'm SUPER impressed with the quality of the machining on the alum top. I love how the LED cutouts are done - with the pinholes on top of the dome cuts. I got the angled bottom and it is SOLID. I'm still going to toy around with different spring weights for some of the keys before I solder it together - I only got 60 of the 65g Zealios. I'm thinking of mixing some other springs with Gat linears - 65g Zeals would be roughly equal to what actuation weight? I have some Sprits 78 (2 pcs), 72, 62 and 68 (which are weighted for total compression) and some Gateron springs (massdrop) which are weighted for actuation at 62, 45, and 80 (super heavy). I've got more gat browns if I want more tactiles, but if they are going to be different I might as well do linears, is my thinking.