i dont look at the relation between the two cards to determine balance, usually one is just better than the other in some way. nova/sn generate more net quanta, the immos generate more net quanta. 5-10 just happens to be the boost from the upgrade. and it will probably be lowered to 4-8 if i ever redo the cards.
if you want, you can compare it to rustler, whos quanta generation doubles :p