When I first bought my Pilot 111 it occasionally switched itself off, so I returned it to the supplier who replaced it. The replacement has been fine.
Regarding signal loss, I have only once encountered this. I was RH seat in an AA5 above cloud over the Lake District. Both me and the P1 had our Pilot 111s, and both units simultaniously lost signal. P1 had a remote aerial, which we tried in every possible position. I tried holding my complete unit at all available windows - to no avail. They both recovered at the same point about 30 miles further north. There was no notamed deliberate jamming, so it remains a mystery.
I usually use mine in the Chippy, mounted on the coaming. The perspex canopy means I get a good signal withpout the need for a remote aerial.
SSD