Ohh I see, thank you very much for the answers!It should allow perfect framerate emulation as synchronisation is done with the audio buffer (which define the rate itself), as rendering will wait for audio frame end. For example, and as you noticed, most games doesn't run at 60 fps in real world, some may run at 50; 55; 59,xx (neogeo I think). So it can produce a "frame-skipping effect" but no frameskip occur, it's just more like it was running on real devices (if I implemented this right...).
I've researched a little after your answer and looks like Midway Games like Mortal Kombat ran at 53hz refresh rate on real hardware, cool stuff to know, I appreciate all the info