The worst fright I ever had was in my Arrow 1 into Birmingham. Forecast FL was about 3000ft and I had enjoyed the sunshine in the airway at FL070 for the previous hour before being cleared to descend, entering cloud at about 5000ft. I knew there were no obstacles in the warm air below but I couldn't believe the rate of ice buildup -- the temp probe atop the windscreen became fist-size in less than a minute, prop ice caused so much vibration that I throttled back in case the airframe was shaken to bits, I fancied the controls were getting sloppy. ATC was brilliant, clearing me immediately to 2000ft and warning other aircraft in the TMA. The ice cleared in seconds from 3000ft but when I returned to the aircraft seven hours later there was still a chunk of ice in the air intake. Never again. I can only imagine the terror of those two people in the Malibu that night.
Also on this type of flight there is usually the human factor element of the pilot being under pressure to complete the mission. Non aviators often do not understand that flights sometimes have to be cancelled due weather etc.
Many years ago there used to be numerous illegal charters to the Isle of Man at TT time. I watched as one PPL dashed out to his Cherokee and took off VFR to retrieve the punters he had taken across earlier that week. Mist/low cloud was covering the south of the island and he flew into rising ground north of Chicken Rock/IOM VOR. Some thought he had mixed up his radials, some thought he had tried to use the offset VOR, I thought thank goodness he killed himself on his way to pick up the passengers rather than on the way there. I fear this Wingly thing is a disaster waiting to happen even without the perils of icing in a piston single -- or even a light twin -- or even a very heavy twin, for I recall a ice-related fatal in the Spanish mountains which claimed one of the finest pilots who ever gave me an aerobatic lesson.