I know many user do not use AccuFeel but there are a lot that do. The current version which was of V4.5 is accepted by V5 and works it seems without issues. How well it does what it does at the sim ESP core engine level has always been a mystery to me but the proof was in the a change in sounds etc and general flight behaviour with AccuFeel on for various models. Part of the AccuFeel application included the ability to tweak water behaviour in the sim (remember originally this was FSX) so you could change the wave motion, water drag and sea effects with it, effectively producing wave motion in FSX. 

The need to do this of course changed with the introduction of NVIDIA wave water algorithms in P3DV5. I had been constantly perplexed as to why I was getting large swells and unrealistic waves not to mention some crazy behaviour by amphibians and float planes on water in a way that I sheeted home to some error or scalar issue with NVIDIA's wave motion. WRONG it seems AccuFeel was silently working in the background to upset the wave behaviour still manipulating the sim core engine physics to create wave motion, water drag etc. This had the effect of seriously magnifying the wave action in sim. I went down many rabbit holes including Active Sky injection etc to try and resolve why a stable aeroplane had turned into a wild bucking bronco on crazy waves. SOLUTION opened up AccuFeel turned off the wave effects or sea effects but left the other aerodynamic stuff on (sound etc). The transformation was an education. Waves no longer became huge swells, wind direction was at it should be and all those aeroplanes that can live on water returned to being well mannered and controllable, real wind and weather accordingly. So it seemed AccuFeel did do what it said in the way it said it did but this was not a good outcome now with NVIDIA wave motion in P3DV5. 

So if you fly floats and use AccuFeel do not worry about the hard fix altering the contact points using the switches: //always_use_avg_surface=1 or //ignore_waves=1 but just turn off AccuFeels sea state and wave controller!.

 

Interesting. I had not encountered such issues with my combination of AccuFeel and P3DV5. But, I only fly amphibious aircraft (love the MilViz Beaver) in calm skies. I personally think the Nvidia water engine to be ghastly, and basically turn it off so perhaps that is why I don't see the issue.

What I found addictive were the sound enhancements. The waves slapping at the pontoons while sitting cold and dark sound amazing, and the water noises at take-off are great. 

However, I will keep your observations in mind if anything runs amiss.