I was planning to apply for the Amex PRG too, and keep my Zync card knowing my Express points would roll into the PRG. A bit off topic, but I've tried several times over this weekend applying online via my Amex account for the PRG card (started Friday evening..it's Sunday evening now) and I keep getting a spinning wheel timer when I apply for the PRG but no screen comes up after keying in my CID number (the 4 digit # on the front of the Zync card). I have waited over 10 minutes and can only cancel out of the connection. Can't figure out what's causing it as I've cleared cache, cookies, and enabled/disabled pop-ups, rebooted and the problem still occurs. I'm using a newer MacBook Pro. Very very frustrating...This also occurred when I tested out applying for the Platinum card too.
I posted on CB about this and was told it happened to someone else also and the only way to resolve was to call into Amex and apply by phone which results in a hard pull whether you're approved or not which defeats the purpose of not getting a HP if declined. So if the OP gets the spinning wheel problem be aware of the HP that's coming whether you're approved or not for the PRG.
Thanks to this thread I think I'll just wait for a bonus offer now though! Maybe they will get the spinning wheel issued resolved in the meantime. I'm not in a hurry to get the new PRG but definitely want to roll my points into MR points stead of Express points with the Zync card.