First off: Greetings Forum! I'd been hanging around reading on the interesting posts around here and figured I ought to start throwing my two cents in aswell.

To the OP: I too am a little frustrated/confused with the current SP system. Mostly because when you first start the game at lv1 you can do 4-5 star leves that net you over 1000 SP per kill, which is really incredible to start off. However, after you crack the lv20 mark your SP reward from leves starts grind to a halt around 200~300 which seems rather unfair. Granted, leves are going to change so I can't really say much about the SP from them until we see how it plays out.

Now then, I don't see anything wrong with the current SP curve, seeing bigger and bigger numbers each time you level up adds a bit of a challenge factor, what I think would be a better solution is to gradually increase the amount of SP you get from monsters your level and higher as you level up.

(I'm going to use figurative numbers here since I don't feel like looking up the actual EXP figures) If you needed 10,000 SP to rank up, and even-leveled monsters gave 200 SP per kill, then you would need to killl 50 monsters to level up. Now when you rank up you could need 13,000 SP to get to your next level, but now even-leveled monsters could give 225 SP per kill. This would equal out to 58 monsters needed to kill to next level. It would still keep a curve (each level being harder and harder to get) while providing a greater sense of accomplishment to the grinder.