The routers I bought from Ebay won't arrive till tomorrow. So no update on what REv's they are. However, just some more information since I have been using this Rev C one in my home/office. Ironically my home office is probably a more taxing on a router than any of the businesses I take care of as I have two teen age kids who are always either gaming or streaming netflix, along with my wife streaming netflix and often myself as well.
Overall the performance seems great. How is that measured? My son is yelling at his computer while playing League of Legends and saying "This stupid LAG!!!". So performance wise we are good.
I was dorking around today and wanted to make 2 changes. I wanted to name the router mytechco and I wanted to name the local domain mytechco.com
I did that and hit save and instantly got the error 413 - Request Entity Too Large. I instantly rebooted the router and made the changes again and hit save and it worked.
So my theory (probably wrong, but what the heck) is that when the router has been running for some time, I assume there is memory in it that is being used and over time it is used effectively to cache things (call them what you will, routes, dns resolutions, or whatever else a router might store in memory). At that time, if you try and make a change and there is no more capacity to temporarily store the changes, it throws this error. As soon as you restart (I assume clearing out the memory) you can now quickly make and save those changes before the memory is all used up.
Again, could be totally off base, but my only guess at this point.