I have no problem in trying such devices -as long as they can be isolated quickly!
If device is 'fixed' to aircraft then different matter entirely......
We tend to get a bit touchy about using the aircraft power source for such devices but let's not forget that we are usually talking about low-voltage devices.
I would certainly think twice about plugging some homemade kit into my 240v AC domestic supply but you'd be amazed what uses pilots conjure up for a 24v DC supply !