Speaking from a merged server I can say top 20 would cause the top to get even further ahead, I'm top 20 so it wouldn't make a difference to me but to those behind me it would be, the only problem we have atm is as someone else mentioned the competitiveness over the SS-ranks, it can be a real pain sitting there clicking a refresh *on for over an hour or so.
My point being top 50 is just fine as long as your server is active enough that is tho...