Aside from the rules which makes it a moot point:
Having likely raced more SS'rs than most on here.. I can tell you in certain situations I personally prefered a single seater at that time. In shorter loop races and areas like Parker, Barstow, certain parts of Baja or Lucerne where I knew the area, courses and/or had prerun extensively; I seemed to focus more in an SS and in retrospect liked not worrying about the other person, but I still drove as hard in 2 seat cars. Now that I'm older I like having a co-dog with me...
On longer events and or bigger/single loops I think the Co-dog and the extra eyes are more useful and having a hand with a tire change or issues is awesome. Now that GPS has become so engrained in the sport, a SS actually gives up something to a 2 seater as now you have the ability to use the tool as an advantage as opposed to a SS'r where GPS is just a reference to make sure you are on the course that you cannot fully utilize with one set of eyes.
Another advantage in the buggy classes with limited HP where you have a lot of single seaters like classes 16 12,10 & 9 was weight, and making them narrower and more streamlined. But with the UTV drivelines where they are in some models, it's not as feasible to balance a car with a center seat.
Most true drivers will not factor in the concerns for the co-drivers and will drive the same w/wo a passenger... Now if you want to level the field: Remove the GPS and race on the markers like we did on ATV's & bikes or just give a reference to course direction or limit zoom and you'll see who a good driver that can read terrain is vs a guy with just balls or a lack of common sense or people that race on daddy's & or sponsors money... IMHO it takes a lot more skill to race a car w/o GPS.
We raced the SF 250 this year and our GPS had a total hardware failure at RM 35 and we went old school off ribbons, arrows and sight and some knowledge of the area and we had a ball! Reminded me of the good old days...
Back on topic-sorry for the derail... I was hoping Harvey Mushman would win the Henderson 160