I think anything above 5000K is unhelpful in veg. I've vegged under HPS with good results.
For this setup, I think you'd kill it with 860W CDM lamps from Philips. The lamps must be vertical and your umbrellas fit the bill. The only problem might be that they need magnetic ballasts. My girls go batshit in this light, 93 CRI. I bloom under them, too, love the frost and compact structure vs HPS.
The only thing to keep in mind is that you need to run them on 208V to get the 860W. If you run standard single phase 240V you'll find those ballasts pulling all thousand watts- plus 75-100W each for themselves. They're a great light for the job but they are not super efficient. That said, they last three years and MH lamps aren't very efficient, either.