They do lay to full potential, I wonder though if they starve to death in a dearth. If they want to raise brood like they do now during a dearth, you would go broke feeding them, lol.
I just checked up on my 2 Sunkist hives for the first time in 10 weeks (long story). We are in a dearth right now, as just about all of summer is. The 2 Sunkist hives had more honey left over than any of the other 6 non-Sunkist hives. In addition, nearly all 6 of the other hives stopped rearing brood, waiting for a flow of some kind, but not the Sunkists. Both hives had every cell full, of either brood or honey. I don't know how they are still rearing brood without consuming the honey, but I don't really care. I'm a happy camper!
Why are these queens only now being offered if they’ve been using them internally for all these years?
Dr. Russell was selling them before. Has been for nearly three generations (or is it four now?). Only up till this year he was selling only to commercial operators. They booked his orders. He tells stories about some commercial operators that send him a blank check and write in the memo line "send whatever you can."
From what I've gathered, Dr. Russell decided to make the strains available to the general consumer, more as a betterment to the beekeeping community. He doesn't make much of the hobbiest (or sideliner, really) but he still bends over backwards to help you out, all in the name of the beekeeping community.
has anybody provided a number of eggs per day a Sunkist might be expected to lay?
No clue. Send Dr. Russell an email, he might know.