For just cleaning 1400 to 1800 psi (the range the electrics run in) is fine. For heavy duty, stripping decks, long distance cleaning, etc. you will appreciate a higher psi gas model.
I get pretty good foam from my 1400 psi and realize water softness. amount of soap (use around 1:10 in bottle), settings, etc can affect results. I do not see that much benefit from shaving cream foam except it is cool but the near shaving cream sticks long enough to do what it needs to do, My "cleaning" soap combo is Adam's plus an all purpose cleaner. I just use straight soap and let it sit when doing a maintenance wash usually after a good pre-rinse.
I agree that getting the unit out and putting it away does add some time to the total process but you will find you use a LOT less water and generally safe with the fan spray setting.