I was looking at a few options as replacement to my bicycle saddle. I have seen these used majorly with roadbikes than MTBs, but I didn't understand in what sense these should be preferred over the ones with no hole, if I may call it so.
The idea of the hole is to allegedly relieve pressure in the groin area. Works for some people, but depending on the shape of your groin, the edges of the hole can put more pressure on the groin. Part of this is due to hysteria to alleged impotency of riding a bike, and part of it due to it being more comfortable for some people.
As for MTB vs Road, there exist plenty of saddles which have this feature of both types -- the distinction between MTB and Road saddles is primarily for marketing, though the MTB saddles may be built a bit tougher (e.g. rails or something). The important thing is to have one that fits.
Saddles are in their very nature uncomfortable when used for long periods of time. A hole may help with ventilation and pressure on the groin, but any exaggerated claims about this design are unfounded. I use a saddle with no hole (a Brooks) that is comfortable and I've used cut-out saddles that have been comfortable, too.
You want a saddle that supports you by your ischial tuberosities (the two points at the bottom of your pelvis also known as your "sit bones"). If you don't feel supported by those points, you will be uncomfortable with or without a cut-out.