Post ride satisfaction level would be my concern with a guided tour.
Parkhead Station on the C2C is one of my regular turn around points on day rides, and I often see C2Cers on guided tours.
One mob arrived to be handed bottles of water from the support van.
I'm no cycling purist, quite the reverse as I usually ride an ebike, but not even carrying your own water seemed a bit naff.
Part of the fun of a long ride is using your initiative to route find and sort out snags such as mechanicals and sorting where your next drink/food/bed is coming from.
A small example, when I turned up during a long ride at the cafe at Thorpe Thewles in Cleveland to find it shut, I was pleased with myself when I located an outside tap.
To have everything spoon fed would would seriously reduce the sense of achievement for me.