This line slapping on the rod shaft has been a topic for ages. I wanted to find out. I went to our local park and with my Olympus film camera (That's how long ago I conducted this experiment) I photographed up the rod as the line shot out. As I was using a white line I could clearly see in all the pictures that the line was dead straight with no slapping on the shaft. Contact with the shaft would temporarily occur as the tip recoils after the stop but even this can be minimised by a follow through in the direction of the cast and a slight release of the grip. As the line shoot out usually the rod is still at a slight angle which means that the line will rub against the very outside point of the guides.
On the other hand with snake guides (on all salt water rods) turning the rod 90 degrees could quite possibly force the line towards the rod shaft for more friction.
This is just my way of visualising how snake guides would work when the rod is turned 90 degrees. Again a photo would prove it one way or another.
Frequent line tangling around the rod usually results from hauling across the body, from a shooting basket that is in the wrong position or from wind blowing the shooting line towards the rod butt etc .
I have always been a fan of small/light guides to avoid dead loading a rod. Talking about friction, which is supposed to less with Ridge Lines. Theoretically this may be so, however there is an other matter of more concern to me. The circumference of a round line is say X If you were to stretch out all the valleys on a ridge line the surface area would be much greater. Initially I liked the idea as I though the valleys would hold more floatant silicon. True but that silicon also trapped a lot of dirt. What really put me off these lines is that the valleys also greatly increased the wetted line surface thereby adding weight to the line, which is of no benefit at all.
Cheers
Herb