Joel
As far as the debate between spraying and rolling goes, everything depends on the situation. We are a commercial contractor that specializes in new construction and multi-family is what we do the most of by far. We have 1,400 new units under contract for this year and we do a ton of apartment turnovers and some remodels in between.
Since most of our work is new construction, I would say 95% of the painting we so is spraying. We use most Graco equipment and we have a fleet of 16 sprayers, from smaller HVLP setups to the bigger more intense Airless units. If you do not know much about spraying equipment you may get lost with this paragraph but I will translate it below. The machine we use the most by far is the Graco 1095 because it is so versatile, it can be used to spray almost any material and it sprays as fast as we can keep up with.
Anytime you're using a sprayer, there are 3 different things that you need to figure out. 1 is your spray tip size. The way these are made, they are labeled with two numbers, so for example let's say you have a "525" spray tip. The last two numbers will let you know how much paint will come out of this tip if you help the trigger open for one minute, and being a "525" the number is "25" or ".25 Gallons per Minute". So the larger the number, the more paint that will be applied to the wall or come through the gun. The first number, in this case "5" is the width of your spray pattern, and this is calculated by holding the spray gun 12" from the surface you are painting, w the number 5, at a foot away from the surface being sprayed, your fan will be 10" wide. Let's say we have a 217 tip, the fan will be 4" wide from a foot away from the surface and will allow .17 GPM through the tip when the trigger is held open. Knowing these things will help you select the right tip for the job. If you're trying to be more accurate and avoid over spray as much as possible, you'd want to choose a small fan size that allows the correct amount of paint through based on what you're painting. These things can be adjusted in the field, but buy a tip that's close to what you think will work best for your project. Being as we spray a lot of new drywall, we have been using 1235 tips, which have a 24" wide fan from a foot away from the wall and let out around .35GPM of paint (which is among the largest available sizes they make). This allows us to get the job done faster.
I ALWAYS recommend all sprayed on coats out of an airless sprayer be backrolled. On our larger projects typically we have one guy spraying and two guys backrolling to keep up. Backrolling allows product to be spread on evenly and uniformly and will give you a much better final product. (It is a very hard to spray any surface evenly without backrolling). On smaller projects we usually have a guy spray and backroll himself. One thing I always tell our guys, make sure you go back and LOOK at the work you did to make sure it looks even and uniform. If you are apply a product w a sheen, the light should reflect evenly even after paint has dried. You should be able to move and look at the surface and you will be able to see imperfections reflected in the light. It's always easier to fix things before they dry. If you wait until later, you may have to do the entire wall again or the new area may reflect light differently than the older.
Also, start w your pressure on the lower side and dial up as you go. You can always turn up the pressure but you do not want to start with it too high or you could make a big mess.
When trying to decide spraying vs rolling, try to judge how many things need to be covered that won't receive paint. If the time and costs of these things (masking tape, plastic, respirator filters, spray suits, demasking) exceed the time and costs it would take to just cut and roll it, you're better off just doing that obviously. Although some colors can cover better when sprayed, and if it would take you two coats to cover if rolled and only one if sprayed, spraying might be the better solution. Of course availability, experience and access to equipment may make that decision for you.
I hope I have been of some help. If you need anything more specific please let me know!
Mark