That cob has a forward voltage spec'd at 52v. The LPC has a constant current range from 9-48v. Probably not enough to run that one.

When I first built my fixture, I used Angelina reflectors on my Vero SE for almost a month of constant use with zero issues. I removed them because I found that I was able to get a more uniform PPFD across the canopy.

I hacked an old King 1200w fixture and used the Vesta strips. my driver pushes them @670mA and they are a huge improvement over the epistars. I'd think that since the forward voltage is the same for both the proportions of the drive current should also stay the same.

I'd think that you should be ok to initiate with the 5k. Once you get fully into flower I would try to give them a spectrum a bit better suited for flower.