Just wanted to throw my hat in the ring. Here's my setup:
Verizon FiOS 75/75 service, using their ONT -> VZ Provided Router via MoCCA.
Almond+ Running R066 connected to VZ Router via Cat5e, running in AP Mode, as the main wireless network in the house (VZ router's wifi is turned off)
Several Mac and iOS Clients mostly all running on the 5GHz channel, with a single security camera running on 2.4 GHz. The security cam is a G client, so it drags that whole network down and thus I try to keep everything off of it. Most of the Macs and all the iOS devices are N devices. 1 Mac is 802.11ac capable.
I first noticed the data corruption trying to download the Xcode 6 GM DMG (I'm an iOS Developer) and getting consistently corrupted downloads. Ended up downloading at work and was fine. I finally realized it was an issue last night trying to download the 10.9.5 combo update (
http://support.apple.com/kb/DL1760?viewlocale=en_US&locale=en_US) and consistently, over 20 times, getting invalid checksum errors trying to mount the DMG. None of my iOS devices could update to iOS 8 either, like others have mentioned. I connected in via Thunderbolt->GigE direct to the Almond, and it downloaded fine.
I tried swapping from the WAN port to one of the LAN ports, to no avail. Switching to router mode *did* fix the issue, but now I can't (easily) access any of the stuff on my main network. Yes, I know you can just punch in an IP address in Finder's Connect to Server, but that's not going to work for the non-technicals in the house. The location where the FiOS enters the house makes running ethernet prohibitive without first pulling the current Coax cable out, so yeah, really need AP mode to be serviceable.