Having a cap for sp puts the game on easy mode and encourages unskillful play. There is no danger in a mob only 10 lvls higher and killing things higher for the same sp is the same thing as working for free, o ones gonna do it. A full rank 45(for example) should be able to grind on rank 60-70 mobs. These mobs are more challenging, take longer to kill and therefore should give the big sp we are being deprived of. A rank 60-65 mob that takes 1-2 minutes to kill should reward around 750-1000 sp. The technicalities would obviously need to be worked out but my point is a lvl cap (especially 10 levels) is severally hurting the game.