Umm..OK. I hope I didn't hurt your feelings as it seems you took offense for some odd reason. I think I made it clear what I considered the pros and cons of each method.
What do you want to know about the forces? Constant charge, charge migration, and displacement are nothing new and have been discussed on HF in the past (I can't recall the threads but I'm sure this thread has information on those already).
I agree that there will be people that want to get rid of any potential distortion and that's a good thing. I was just pointing out that the displacement is so small that the added distortion is going to be very small as well. Here's the thing though: displacement will still exist to some degree depending on how evenly you coat the sides. I think it would be really hard to get the exact same amount of coating on each side of the membrane by hand. In fact, you could theoretically end up with more displacement than if you had just coated one side from the start.
I'd wager that the coating outweighs the membrane pretty significantly. Of course this will depend on which coating you decide on as well as how much you apply. If you can provide me with exactly how much coating you are using on a single side I can provide you with numbers.
Regarding my last statement, I'm simply talking about the uncoated side of the membrane (in conjunction with the stator on that side) being much more immune to things like dust and humidity since the membrane is essentially insulated on that side. wachara can correct me if I'm wrong but I think this is why he chooses to coat one side.
I'm not trying to discourage you from coating both sides. This thread is all about experimentation. I think you should try both methods and report your findings.