This is an old Thread but why not give my advise and opinion?
I have a 400w HPS Sunburst (with the 430w sonargo HPS Bulb) for flowering and a 250w MH grow max Jr. (Sunburst??) for veg. This combo has worked well for me for 2 grows. The enclosed ballast can cause some high heat issues in small spaces or in under ventilated rooms.
The 250w MH Agrosun IMO is best used for veg. You can flower with that bulb but MH is mainly used for the Veg cycle. Depending on your space, IMO, 400w or larger HPS would be ideal for flowering 6 girls.