I could be wrong, but I'd rather tear into a CZ75, or P07/P09 any day than a BDM. Then again I've only been into the BDM once, to replace that broken firing pin and that's just the slide, not the frame.
I can't see the sear, the sear spring, firing pin block lifting arm or the spring for that being the issue. Now, a safety shaft diameter issue? Or a slight misalignment between the safety shaft and the two holes in either side of the sear cage - or the hole on the right side of the frame? Or even some issue with angles/sharpness of the detent in the left side of the frame and the safety shaft even.
I know I made the thumb safety on one of my M&P's "more positive" by removing the safety lever (one piece that protrudes out the frame on each side) and using a 3 corner file to make the notch in the safety lever "sharper." That gave it a combination of a more positive feel when moving as well as taking a little more force to make it move.
I've not had to go further than just working the safety on/off so I can't say I've really looked closely at the detent and safety shaft engagement surfaces or angles to see what might be changed there to help. In fact, a few people here have expressed the desire to make their pistol's safety more positive and the usual recommendation is to buy/install a stronger spring (the one in the frame that pushes the detent against the safety shaft.) But, before I'd modify that spring I'd look at the fit/finish of the detent and safety shaft and see if I could take care of it there first - if I had to go beyond wearing it in by hand.
Good luck with it.