Not JS but I've had stockers on a small scale on and off for many years and I lost my a$$ on a larger scale as a young man.
For a set of calves everybody has a different protocol as to what they feel works best for them
A set of calves that are half assed weaned and not given the proper attention( vac's, meds, started eating good, pulls and meds) would be worse than a set that are unweaned that gives you the ability to start them right.
Just my thought
Back to the op
I don't see but a 100.00 between 400 to 600 calves
Add in vac's, meds,death loss, trucking, commission and etc
I see it as a loss
With that said most times money is made when you buy them.
The .10-20 premium for video auction from what I've seen are home raised cattle with good genetics and a past history of performance
As said before its very tough to put a uniform group of calves together
If you're buying a set of calves from one raising then that helps a lot
I think you'd be better off taking them to 800#, but in this market it's a risk
If you can get them bought right and sell them when spring fever hits you may hit a home run