I can see a durability issue with the single foot guide. If you bend it by running them into something, then try to straighten them out (too many times), it is possible to fatigue the guide and break it off.
... I feel the line doesn't run as easily through foot guides than through snake ones... (jpbfly)
Could this be because when the line runs through the single foot guides, it is hitting them striaght on (perpendicular) causing friction? Compared to a snake guide, the line is hitting the guides at a less sever angle because of the "cork screw" design of the guide? so there is less friction...
But that line of thinking goes against randyflycaster's comment