My 8th season with Vibrams, 3rd pair, Signa model now. Never had any issues, and I think a lot of above is due to a small or tight straps.
I'm using only North NTT's straps on all my boards and would not blame Vibram for straps or foot problems, particularly Signa which is ultra low profile almost like a sock. Comparing 5 fingers with one toe is like gloves and mittens - no comparison, sorry.
The grip with 5 fingers on board is absolutely fantastic. Not to mention self draining with Signa, which wasn't the case on previous models. And no, they do not take sand
A small shell, here and there yes. And it's annoying.
Durability might be the issue only if not dipped in tap water after the sesh. Riding 150-500 hours each year, figure out...The loop on top is for drying, use a peg. Do not leave them on the Sun to dry, coz heat WILL slowly kill it. But that's valid for wetties as well, isn't it?
Trying it is a must before the purchase. Half the size difference is a no go. Awkward foot is a no go.
This topic is prone to individual experience with the shoes of all kind
One shoe does not fit all.