I'm going to "self nominate" myself as ONE of the resident detailers on this site (I know there are several so I won't claim sole ownership of that title lol).
That being said:
Yes a foam cannon is a MUST for someone who notices even a single swirls.
No, a foam cannon is not a "substitute" to washing the car. If the proper chemicals are used (Maxi Suds were mentioned and that is what I use as well), then a foam cannon will encapsulate the loose dirt particles and prevent them from swirling the paint.
A 1400 pressure washer is worthless. I use a 3000 psi 2.5 GPM on my customers cars. You need at least 2200ps @ 2.5 gpm (most of the 1400psi models are only 1.5gpm and that simply isnt enough). Even with my 3000 psi, I still find a neglected paint job will not come clean with just a pressure washer. The dirt embeds itself into the paint it seems and cannot come clean without elbow grease.
Use a foam cannon, use a two bucket method with grit guards, and use two mitts (one for top half, one for bottom), if you are as anal about your car as I am.