The bulb certainly does matter.
For 400 Watt magnetic, CMH looks pretty with its white light, but it sucks big time for flowering. A cheap GE creates massive results. Never tried a Hortilux in 400 W size.
For 600 Watt Digital (Lumatek), the Hortilux loses light output too fast (as measured by a meter). Bulbs need changing in 6 months. Heard rumors they have fixed this, but don't need to waste the money to test.
The Sun Pulse, like the CMH, looks pretty but don't waste your time, yields and quality suffer.
The Digilux and Plantmax produce good results with decent life.
So far, the differences in bulbs have been dramatic. No need for extensive testing. If you wanted to test Digilux/Plantmax/Ushio/Lumatek, that would take some doing. Someone please go for it.
In summary, you don't need the blue light or wide spectrum in flower. You also don't need the most expensive bulb. You should get a light meter so you can tell when to replace your bulbs.
Build a bracket/sling for your light meter that attaches to your fixture so that you can locate it in the same place every time for every reading.