Gabapentin is a fun med, but only the slightest bit. As Penguin said, it's "pleasant."

If you use it regularly, there's no benefit to going above a certain dose. If you're prescribed 600mg 4x/day but feel better with 900 mg, why don't you just take it at 900 x 2, and 600 x 1? It lasts forever, IMHO there's no need to take it 4x/day.

As always, YMMV.