Well, after a while of being set on the 1TB Fusion Drive, I have decided to just go with the standard 1TB HDD in the new 27"... here is why. I am placing my bets that every new 27" iMac has a slot for Apple's proprietary flash module (which OWC already has aftermarket modules for the rMBP, and they look to be the same ones in the new iMac), and that the display will be able to be removed in a similar fashion to the current iMac (held in place by magnets). If I am correct about these 2 points, which both make sense to me, I will be installing my own flash module sometime later down the road. I have also read through the AppleCare policy and it doesn't say anything about voiding the warranty by opening the case, it just states that the aftermarket parts will not be covered. So, the configuration I have now settled on is the top 27" ($1999) with the 680MX graphics (+$300ish)... RAM and SSD I will do myself. Might do the i7 if the cost is around $150 (retail difference between the two CPU's is $110, so it should be in the $150 ballpark).