Another case of sensationalism in advertising.
All HPS bulbs emit roughly the same spectrum of light across the board, as do MH bulbs, whether its made by Phillips, GE, or Sylvania, or whoever.
There are also what are known as "Conversion Bulbs", basically an HPS bulb with an added filament that emits a Bluer/whiter light. They also make basically the same thing in an MH version. These are OK if you only have one type of ballast.
Concern yourself with the lumen output. I tried both the GE (Chromalux) and the Phillips version. I was disappointed with both. They have around 12K less lumens than thier counterparts. I can't say that they won't grow good dope since I didn't bother to use them for the entire grow. But I do know that you lose alot of light with them. They are touted as the BEST light for every stage.
Are they really?
I do know that given the choice of 400w bulbs, I'd rather run a 50K MH light for an entire grow rather than a 30k dual spectrum bulb any day
Now I HAVE seen a SonAgro bulb advertised, that purports to be 430w. That MIGHT offset he light loss, but I couldn't say, never having one in my hands.