AIC Micro's a little funny. They have "Available: Y" in the 8RDA+ description, but say "Backordered" in the title. Seems even they're out of stock now. The non-plus version is widely available, so one could get that if they need it, but, it's up to each person to determine if they can take the loss of features for the savings of a few dollars. Of course, at some vendors, the price difference isn't so small *cough*NewEgg*cough*
I've seen it from enough sources that I believe it (re: the PCI lock). I've got a TV tuner/capture card (the Leadtek Deluxe) that was NEVER happy when the FSB on my old motherboard was 166 or higher. Since it's given me nary a hiccup on this setup, it's good to know that it's actually true.