Thank you very much for your reply! I've never tried to sharpen pictures in LAB mode. I will do a test when I have time to see if I can notice any difference between sharpening in LAB and RGB mode.
I use the high pass filter to sharpen my pictures but I don't think there are huge differences between different sharpening methods. I guess it's just a matter of preferences or habits. Besides, a great picture remains great even if it isn't the sharpest picture in the world. Of course, sharpness is subjective and what looks sharp to me might not be sharp enough for someone else or vice versa.
Thanks again my friend!
With Friendly Regards,
Dromaius novaehollandiae (44)