www.makemkv.com

So if MakeMKV version 1.15.3 handles read speeds more actively, does this mean editing the registry setting by using the 0=99 string for drives like the LG WH16NS60 would have no affect/impact starting from 1.15.3? By the way, I flashed my WH16NS40 NS50 from the factory installed ROM version 1.03 to WH16NS60 MK version 1.03 .

You still need to enable speed control. The difference is that with 1.15.3 the generic 0=99 works fairly reliably.