moving up limits or multi-tabling

[TheEye]

The facts...

Several months ago used to win around 2-3 BI, 2/4, in a 6 hour session, playing 2 tables (+a few nlhe) on ps.
(during the billionth promo, in an aim to boost vpp) increased the number of tables to 4, but ev significantly dropped to +1BI/break-even, but would still manage around +3BI from the fpp gained (excluding the vpp milestone rewards).
From day to day would switch from 2 tables to 4 and back depending on moods and the same applied.
Now thinking, whether it would be better to move up to 3/6 or 5/10(tougher games) 2 tables (+5-6 nlhe) or 4 tables (+2-3 nlhe) at same limits and aim at supernova elite(will start playing regularly unlike at present, but maybe still impossible, however many vpp milestone rewards on the way) next year.
You do gain more vpp playing stud(limit) than nlhe(lower limits).

General suggestions on multi-tabling vs moving up?

ty