I tried to a few times last year and earlier this year but initially their shipping costs were crippling and after they revised them they didn't seem to have what I wanted in stock. The new Solskins weren't ready when I was looking for boards and they don't have heatsinks in any case. I'm not sure how you run 576-675 LEDs on them without a sink, though I understand they advise using 3mm plate aluminium and provide a template for creating your own.
Price-wise, they are pretty much inline with HLG when you factor in shipping, GST and conversion rates, but HLG had a really good deal on the QB324 boards with heatsinks, and at the time I bought them there was no 10% goods and services tax on overseas purchases under A$1000.
So a combination of timing and price, I guess. Also, the 12"x12" Solskin boards aren't ideal for a 3'x3' space - two QB324 boards provided slight better coverage and more power. I also have the option of Samsung strips, which are great for veg frames etc and are pretty cheap. Strips on a 2'x2' frame are a good size for a 3'x3' space.
Purchasing heatsinks from China isn't as inherently risky as buying LED boards, because it's just a bit of extruded aluminium. You may get a slightly thinner gauge than you specify, but it's easy to spot - as are any other issues.
I've always been in two minds about Chinese boards: yes, they're cheap, but it's hard to trust you'll get what you ordered. I wouldn't mind so much if they said "Here's a cheap LM561B board - it is what it is", but no, they have to try to sell it as an "LM561C S6" in an effort to hoodwink people into believing they are getting a much bigger bargain than they are.
Just stop all the bullshit and sell products for what they are - many people would be much happier about purchasing them if certain Chinese vendors were more honest.