I’ve had the BK Gamer Plus for a couple of weeks now, so I thought I add some feedback here for anyone looking to get one of these.
It took me a solid week of tinkering to get it working to where I was happy with it. One of the problems is that a lot of the information on setup available online is based on the older version “Gamer 2” and doesn’t consider the new features in the Gamer Plus.
One thing that tripped me up was that many people recommended using a second usb sound card and/or voicemeeter to isolate sounds and haptic feedback. I later found that neither of those are needed. The Gamer Plus has a usb connection which allows it to act as its own sound card. Now I run the Buttkicker 3.5mm audio to my motherboard sound card and also have the USB connected.
To achieve both audio sourced and game telemetry-sourced feedback I run both SimShaker for Aviators/Sound Module and HapiConnect from Buttkicker. In Simshaker I set the dedicated sound card to the 3.5mm Audion connection on my MB. In HapiConnect I set the outputs to the Buttkicker USB connection and my speakers/headphones. The result is FANTASTIC. HapiConnect produces feedback from deep bass sounds and ignores sounds from things like radio messages. Without HapiConnect you won’t get any feedback from things like flak or sonic booms. Once you have this setup go out and fly through a KS-19 100mm AAA barrage! 
The other thing I struggled with was a very annoying intermittent buzzing when flying the viper or hornet in DCS. At first I thought there was something wrong with my hardware setup/connections and wasted a ton of time switching inputs/outputs around to resolve this. Finally I isolated it to Simshaker produced feedback. The culprit was the “Flaps Movement” setting in Simshaker. Even though this buzzing was occurring when I wasn’t manually moving the flaps the viper and hornet make tiny corrections to flaps position in auto mode and results in this “buzz, buzz, buzz” that was driving me insane. Thankfully SimShaker has a setting to correct this without turning off Flaps Movement all together. Under special options change the “Flaps Movement Filter” setting. I currently have mine set to 40.
I have to say the Buttkicker is one of the best simpit upgrades I’ve done in a while. Although the setup was a bit frustrating it was well worth the effort. Flying through flak, feeling munitions come off the wings, sonic booms… I could go on and on about this. It’s so great feeling the aircraft react realistically. I know why people would say they can’t fly without one now.