My one issue with that is what you are referring to...PvP people going to a PvE server to join some hardcore PvE guild, get high-end tier gear, then return to a PvP server? That idea doesn't seem right imho.
I'm not sure this is even an issue. The pvp realms host more successful pve-oriented guilds (or did when my wife went looking) than the pve realms. We felt it was from the same effect we see in our raid groups on our pve realm: those that know how to pvp are generally better at playing the game.
So once someone levels on pvp and then chooses to participate in pve content, there's something they've already gained that doesn't get learned as quickly the other way 'round. I believe it's speed/reaction time. We've had raid members that were devoutly against pvp, even in small doses. "I rolled on a pve server for a reason," they'd say. Or even as far as "pvp sucks shit," and the like. Those folks had terrible reaction times and poor management of the global cooldown.
My take on all that is that the survival skills required to stomach leveling 1-60 in the pre-BC content was a very serious filter. Those that couldn't pass muster had a few choices: reroll or (later) transfer to a pve realm.
Back to the quote, I don't think you'd get more end-game gear on a pve realm. A good player from a pvp realm would probably dazzle the crap out of pve raiders, sure, but there are more raid slots on the pvp realms that seem to be home to a greater number of end-game progressed guilds per realm.
I don't know if this holds true for alliance guilds as well, my wife only peek through the numbers for horde guilds.