This is interesting as I'll be buy a new brush soon too, I started out with the paashe VL and have a BCS, had the nozzle soaking so I got the VL out for a ride, so big and bulky compared to the iwata, but people did some amazing work with those back in the day, it's all the more impressive considering what they had to work with back then.
I've heard of the sweet spot - "tuning in" with your airbrushing and I think I finally found it on my bcs, I want to pull back ever so slightly and have paint come out but I found it takes a little more feel to it, now I'm starting to get the hang of reverse daggers, and practice trying to see how fine a line I can get out of a .5 nozzle, I'll probably do a gradual upgrade maybe go to a .3 nozzle, think I'm digging the SB plus for my next gun, I use cups for the bcs so I think side feed might suit me, kind of funny as a painter I've seldom used a gravity feed spray gun.