Nad
Thought yours was a good post very interesting, i use the Vaq what i have found in short is this, depends on the Mineral makeup of the ground when wet, and yes what is the ground wet with.
For example Relic site in WA west Australia the other day, could not get a good GB on the Vaq, had to turn the Sens down to about 3/4 instead of the 10 i normally run at, bye the way the Vaq runs quiet as a mouse in most places at sens 10, yep under a very old tree was the water table at over 12inches deep, no probs turning Sens down again Ran good but less depth, Dry sand run for ever over 10 Sens/ but wet sand with seawater again have to turn the Sens down a couple of notches, Some soil i go to is very moisty good soil/ this in WA means water is close bye/ floods you can bet in Winter.
So you can Run deep in some moist soil no probs/but you will have probs in some wet soil/sand, sorry nad hope your not bored to death yet,
See ya
Dave/Holey Dollar