OP, if you are going to check out that thread, just a heads up - mine and many other's experiences with differing lighting routines (mainly "pro-24 hours people") were deleted by moderators.
Read it if you'd like and come to your own conclusion, but I thought I'd mention that.
Personally, I've gotten my best results and healthiest looking plants on a 20/4 veg light schedule under a single 1000 watt Hortilux MH. The optimum veg light schedule will in part be contingent upon the type and strength of light under which you are vegging.
I keep all the floro's on 24 now. HID'S I still think the dark time helps alot. If you top water by hand they drink more so watch that until you learn the differences.