Every server I have ever played has been like this. It gives incentive to play a legend which creates a long term player. I normally play the lowest xp rate on a server for better drop rates but this one didn't offer it.
I'd also suggest more than 2 xp rates.
X50 is normal drop rate
X40 is .25
X30 is .50
X20 is .75
Most servers who implement this do not give crazy drop bonuses. You need some sort of incentive because very few players are going to grind a rsps like that because if they were going to invest thousands of hours in a RSPS they wouldn't be playing one. Just my opinion.
Some other nice incentives are double skilling supplies when woodcutting fishing etc after a certain total level. Just my .02