"Top 30% of total players that have Solo Queue rating higher than 1600
Duelist title"
it does not sound a good idea.
It is true that on Blackrock Duelist is pretty common (for a mistake done during Core swap) but for icecrown/lordaeron players duelist is pretty rare (since it is top 3 of 2vs2).
you might consider to change it with challenger or rival instead (I am talking about "Top 30% of total players that have Solo Queue rating higher than 1600" )