Just got mine in the mail earlier this week and put them in the test board. I've been swapping between the two weights, and I'm very surprised how much I like the 40g ones. That said, for some reason I just don't vibe with the 75g ones. (Which is weird because I generally like a heavier key press; I was really expecting that to go the other way around!)
I need to type on them for a little bit longer before deciding, but the 40g Clickiez are a serious contender for my 1800 board. I only ordered 20 of each to try them out, so getting the rest to outfit a full sized board won't be cheap--but what is in this hobby? I'm pretty sure I'll get in on the next round of pre-orders anyway.