If you deliberately only hire on one side of the fence and not both, then of course you will run into problems. Seriously, why not adapt too?
Well Fallen has a very high proportion of archers in the clan, probably the class least affected by ping differences. It may make it easier for you guys to play together regardless of server, but generally I enjoy actually playing with my clanmates, something that likely wouldn't happen in the average clan.
NA guy: "hey what's everyone up to?"
EU guy: "playing siege on the EU server"
NA guy: "oh well I get 180 ping over there. Want to come over to NA_Battle_Community?"
EU guy: "sorry, I get 220 ping on that server"
NA guy: "..."
EU guy: "..."
It's nothing against being a global clan in theory, but in practice it just isn't as enjoyable due to ping. I'd rather deal with the problems of 'shift coverage' than feel a part of only half a clan. Given the option of splitting though I'd take it. Would still be great if there was a way to join battles with other sides though, again I like to see people I never play against.