I run a flex group every week with friends and randoms. It's flex 4 for an heirloom run. I set the minimum bar at 550. I do this to compensate for adding people of which I have no knowledge of their capabilities. I mostly do this through OQueue.
However, when I try to speed things up via trade I tend to get a lot of messages berating me for setting the minimum ilvl at 550. That I'm asking for "overgeared" and "HC ready" people. That I "want to be carried" (I'm 581 so that doesn't exactly apply). I make a brief statement about how it's my run and if they're unhappy with my requirements they can make their own. The complaints still come flooding in though.
I personally do not care because even with setting it to 550 people still sign up and it's a very quick run for a shot at an heirloom, but what is the overall view of setting a flex heirloom run to an ilvl higher than the gear it drops?