Hi Units4me,
I have painted with the commercial Wagner many times before; great for ceilings and undercoating, but no were near as good to finish with as opposed to a brush and roller. Also it is only good/cost effective for large houses due to the time it takes to mask tape and cover everything in site, to get a professional finish. I have seen the Reno kings use it, but realistically, the quality is shocking to finish a job like that. You can only use water based paints through it as well, so you still need to brush the enamel on the wood work anyway. Again only if you require a professional finish, I would suggest hiring one for a day and you realise that the time saving is not that good on smaller properties, only for ceilings and undercoating and to make it cost effect you would need to be painting allot of houses. The main think to look out for with smaller units is the amount of time it holds the pressure for, there is nothing worse than it cutting out half way through the wall/ceiling etc and you have to wait for it to gain pressure. This leaves slight drying lines from where you finish and start again.
Don't know if that helps, but anyway just a suggestion!