Hey, it sounds like the discussion is over and I didn't even chime in.
Here are a couple of thoughts;
I see lots of discussion on weaning weights, weather and workload but less on tying calving date to forage resources. I love my cows but their role is only to harvest and convert the grass i've grown to beef. As such my cows are targeted to calf at the time that suits my grass management system best. I start April 20th because that suits my grass system best. Calving much later is a pain in the butt for me as it doesn't suit my system of rapid moves with electric fence through the fast grass growth period. That's what works for me.
I have a friend down in the chinook country that calved for many years half in August/September and half in April. The advantages of fall calving to him were:
Minimal chance of snow and cold at calving.
Ability to sell calves before the fall rush and declining prices.
Cows feed requirements similar to spring calvers in our dry climate.
Drought protection - able to wean calves anytime from Feb. onwards to sell or graze elsewhere - minimises grass
requirements for cows in a drought.
If he was starting a tractor to feed in winter he could only justify it if they were suckling.
Supplied cattle that were ideal age to fatten off grass in the fall - ie around 2 years old at harvest versus 1.5 or 2.5 years.
Got around a problem of neighbors wandering bulls - their bulls were pulled before his cows were cycling.
Combined with a spring calving herd also gave the following benefits:
Need half the bull power.
Calf all heifers at 2.5 years using fall and spring herds - the extra age allowed his heifers to be managed along with the cows with no extra feeding or care.
Excellent breed back rates particularly on 1st and 2nd calvers due to above.
I thought that was an interesting alternative to spring calving - it certainly worked in his situation.