I dunked mine last week when I hit a wave on takeoff. The rx was waterproofed by putting it in a balloon, held closed with wire ties, so I figured it would be ok in a dunking. Well, nothing worked after the dunking. On closer inspection I found that the balloon had deteriorated since I installed it (this is my third season with the Seawind).
This time I completely encapsulated both the rx and ESC with GOOP. On the ESC I left the heatsink surface clear of GOOP, so it still gets good cooling.
I already put it to the test. The temp was about 95 degrees and my brain wasn't working 100% in that heat. I launched the SW without changing the radio model memory. It was set for my Gemini, which is an elevon setting. It nosed in badly as I applied up elevator and filled with water. Everything was 100% after clearing out the water.
So GOOP or I suppose any good silicone, if applied correctly, works great for waterproofing. The SW lives to fly another day