Keeping the original striker block spring alone will not prevent the drop safety to fail. The Apex striker block has a different geometry than the original one from S&W. I have installed Apex in my M&P9 C.O.R.E that I use as a race gun and its a very nice kit that I can highly recommend for competition shooting.
But installing aftermarket trigger kits in a CCW pistol, especially when it affects the safety functions of the pistol, is not a good idea. Even if someone experienced like hardluck1 never has dropped a loaded firearm, it is a fact that loaded firearms are dropped. It could be dropped when holstering or drawing it, or it could be dropped in an self defense situation.
I highly recommend watching this YouTube video with Massad Ayoobe
I Asked Massad Ayoob About Modified Triggers - YouTube