How is pulling a Step Deck comparted to a flatbed? Loads pay more? How much tarping? Cost of equipment?

I think they pay a little more. Not as much as they used to though.
I would say the tarping is about the same as flats...maybe a little less.
Don't know about the cost of flats. We just paid $43,000 for a 2008 Wilson 53' combo step. Also paid $10,000 for a 48' 1999 Lode King combo step. So it depends.

i prefer flat over step .. the reason... i have needed a load plenty of times to get home & some of those times the only good load going right to the house was a steel load that was rear load & unload. cant back up to a dock & rear load/unload with a step. i used to do $3,500 a week. hauling skidded coils. could not have gotten on that dedicated run with a step. i also hauled for 3 years a lot of $3.00 a mile plastic pipe that needed a flat. also lumber too. if i'm going to be far away from home.. i want the best chance of getting back. that is also why i have a set up where ican haul 50,000lbs legal. i've watched a lot of drivers have to sit & me come & load around them even though they have been waiting for hours ,because they could not scale the weight.

There are advantages to both types of trailers. The main advantage to a step deck is that you can haul taller loads which can pay more money. On the other hand, there are very good paying loads which require a flat. You will have tarping with both types of trailers. There are usually more opportunities to haul machinery or equipment with a step, which can pay well and often does not need to be tarped. With either type, you will need to tarp or do a lot of sitting.