I am loading on my XL650 with a case feeder and a Mr. Bullet Feeder, so all I am doing is pulling the crank, over and over. It has taken me about 3 weeks to crank out 6,000 rounds at a leisurely pace.
9mm seems to have fewer issues with the case feeding, sizing, bullet feeding, etc. All the spent primers come out easily, etc. It just works. Yesterday, I cranked out 1,000 rounds and only had one spent primer that did not come out. That was the only stoppage in the entire session. Not bad!
I also have the bullet feeder for the .40, but it seems there is always problems of some sort compared to the 9mm. The .40 cases don't always feed correctly, I get a lot of primers that don't pop out as well, the bullets I use don't feed as smoothly through the MBF, etc. Then in addition, before loading the .40, I run all of my cases through the Redding G-Rx to get rid of the "Glock Bulge", which is a pain in the butt and a lot of extra work.
Other pistols rounds (.45 and now just starting with .38 spl) don't have a bullet feeder setup since my volume is much lower, so there is more manual work involved, also dealing with SPP vs. LPP on the .45, etc.
With the 9mm, I can sit there and pull the crank one after another without any issues, hangups, slowdowns, etc. They just keep plopping in the tray as completed rounds! I stop to refill the primers every 100, and top off the bullets and cases, and then back to pulling the handle. They just keep coming! Plunk! Plunk! Plunk!
I am not saying the others are *hard* per se, it just seems that I have a lot less stoppages with the 9mm than the other calibers. It could just be that everything is fine-tuned a bit better, but even the cases seem to feed better with 9mm. I used to get a lot of upside down cases in .40, which I never see in 9mm.
Definitely less expensive as well, which makes it easier on the wallet.
