Today I used the foil located just aft of center.
The waves were actually sizable - I could have rode the shortboard (and actually thought about bring out the Greedy Beaver - but like I said a few posts back - I really want to learn to prone foil). Made taking off a little sketchy, but today was the first time I got consistent controllable rides. I had a couple of rides where the foil did not lift - I'm thinking of moving the foil forward just a hair to get lift consistently (without the bucking bronco effect).
I started to feel a "shifting" in the foil - I thought it was the plate connection - so I decided to paddle in. When I got back to the van, I took the foil off and checked the bolts - it was the plate to mast connection. Lesson learned here is to tighten all bolts before heading out. Second lesson learned is to actually listen to the designer/manufacturer and disassemble the foil after every use. No corrosion - but why leave things to chance.