I am only lvl 29 miner but i always wondered whats the use of +SP? The most expensive skills i have need 400 SP while i have abt 430 or something. So lets say at lvl 50 u have 600 or whatever, doesnt matter - Once you used your skills and lost almost all your SP, whats the use of having 600+ SP? It doesnt matter if you have 600 or 800 or 1000 because after you lost the SP, a miner with 100 more or less SP makes absolutely no difference. The only right way for SP is SP regen per node. Stacking SP just doesnt make any sense.