Well SBU beat me to it.
I think that should be the case, allow more international slots and allow the owner of that team to pay the difference. Our US guys are great players but they are not the big names that make avid soccer fans' ears go up. Not saying they should go crazy and have like 5 DP slot, maybe 3 per team, put a cap on those maybe. (Not to mention the US players I'd like Chivas to have are playing in Europe right now...)
I really don't think they should designate US players in those slots though.
DeRosario I knew was Canadian :)