The 550B is an excellent press. I think where most people get into trouble on any progessive is trying to go too fast too soon. When I bought my Dillon 550 I was tempted by the speed too but seeing a few gun blow up over the decades (none of mine, thank goodness) caused me to stop and take a deep breath. Now, about three years later, I still don't use my Dillon 550B as the designers intended.

I take my clean and deprimed brass and run it through the first two stations -- prime and charge. Then I remove the case and set it upright in a block. When I get ready to seat and crimp bullets -- usually at 100 -- I first shine a light into every single case to visually check the powder level. Then I finish with stations three and four. True I can't load 5,000 rounds/hour but I can crank out 100 between coming home from work and washing up for dinner. That suits my needs well enough.