Disclaimer - This post is based on my own experience and what I did to tune this issue and my results. It worked very well for me, but you may have a different experience than I did.
I have 2 of these helis, both with BD3SX's on them. I have finally figured out how to eliminate the elevator bounce (at least on my two models I have). I am using the original taller head on mine still, and flying at 1950, 2050, and 2150hs (mostly at 2050). I fought for months and months trying to get this figured out following directions of many very educated people to no avail. I followed the "latest and greatest" setup method to only see it get worse.
both helis are identical and setup with the following:
12 cell with 5000ma packs
Scorpion 520 ultimate
CC Edge HV 160
CC BEC PRO set to 8v
Savox 2284SG on Cyclic
Savox 2283MG on tail
both have titanium turnbuckles and use the Synergy carbon fiber servo arms.
10 degrees of cyclic and 12.5 degrees of pitch
so the first thing I did to tune this out was get rid of the V201 and V200 firmware and replace it with the older V1.23 firmware.
Head gain - I did set my head gain as they tell us to now, by FFF with pitch pumps until the dolphin effect was the least. I settled on 87.
Gain aileron - I left at the default value of 14
Gain elevator - I turned down to 12
Agility - I set to 12 (that is all personal preference though)
Initial response - same as agility, personal preference
Elevator filter - I settled on 6 here. this parameter is weird, I have actually noticed the bounce get worse when the adjustment made would suggest that it should get better. (if you follow the drop down info box...)
P-Portion - I found that I needed to lower the P portion a bit to eliminate the bounce. I settled on 30. 25 worked too, but it was not any better or worse, so I went with 30.
D-Portion - I found that I needed to raise this parameter a bit to eliminate the bounce. I settled on 15
Decay rate - I didn't need to change at all from default.
Attitude hold range - I set attitude hold range all the way up to 14. there may be a misconception here about what exactly attitude hold range does. it holds the model in the inputted attitude and nothing more. the higher the gain, the harder the heli fights a bad CG, or a gust of wind, that sort of thing. so obviously we want this to be as strong as possible. but it will not try to regain the intended attitude, only hold it. so if you lower this parameter trying to help eliminate the bounce, you may find you get a smooshy heli, or a non-locked in hover.
If you would like to see my file, PM me, or shoot me an email and I will share the whole file with you. I really hope this helps guys that are suffering from this issue, bc the BD is a great unit, but the bounce is very bothersome. I hope they release a firmware update that eliminates this issue, but until then, this is what I will be flying.
My personal opinion about tuning advise given for this unit - A lot of tuning advise gets miss interpreted and miss read due to the language translation I believe....this compounds the issue of some sort of control loop issue that is still unresolved that has to be tuned through... (none of that info came from BD or any BD pilot, that just something that I think personally)