To vac advance or not to vac advance

So got the msd ignition in, car is running great, question is, is there a point to having the vacuum advance/is it bad to have it. Msd says it advances the timing up to 10* at 15 lbs. of vacuum. Currently, the timing is 12-13* initial, 22* mechanical and 34-35* total. Any opinions? As I understand it, the only point of vac adv is economy. 1973 dart, 318