Bollocks. Just don't point the jet at the obvious places where water ingress will cause damage like the bearings, dust seals and fog lights. The Karcher K2 allows to have the soap diluted as you spray it on the bike. There is a suction pipe and the nozzle has a setting for the soap. Not foam lance quality.
Now for the Surfex HD. I use the stuff and it is a degreaser which is useful if you spray the bike with Dynax UC. The instructions says not to let it dry, use on small areas at a time and use a brush to agitate if the grease, wax, dirt is resistant. Best to use a soap that is made for the job and for that I use Auto Glym products. If you are lazy washing a bike then the GS and GSA is not the bike for you if you plan to keep it in pristine condition. These require a bit of elbow grease to keep in good condition. Invest in a blower like the Bosch leaf blower and it cuts down on the time spending drying the bike. Unfortunately a sponge will be needed to rid the bike of dirt. Set aside an hour and a half to do it at a leisurely pace. And get yourself a brush that the missus uses to clean the dishes, toothbrush for the awkward spots if you are so inclined. Don't brush your teeth afterwards with it.