Well, I found this thread when I was looking into Posh because of an invitation email.
I have no idea what criteria they've used for issuing invitations, but I haven't played an online casino is several years, though I did do so regularly back before the damnable UIGEA screwed everyone in the US. I used to love the cashable monthly bonuses that could be cleared on Blackjack, even if it did take 30x or 40x play-through.
Anyway, I played my $500 free chip, about 1/3 slots and 2/3s Bonus Deuces Wild. Ended up requesting a cash-out 2 days ago for $987.
I submitted my documents yesterday, and got almost immediate confirmation that they were received and acceptable, but the withdrawal still hasn't actually been approved.
I will post screenshots if/when something finally happens. Assuming I get paid, I will probably hit a few more bonus offers now and again when the terms are particularly attractive; at least until they ban me for only depositing with a bonus.