Conical head tube: does it really make huge difference? I am looking forward to getting a new mountain bike and in various reviews sites they are really focused on if a bike have conical head tube or not. In many cases it is the first thing listed as pro (or cont in case the bike don´t have it). 

It suppose to make the handling easier. But I don´t really see how that works. It is just another commercial trick or does is really affect the handling a lot ?
Assume we have a tapered headset with 1.5" lower bearing and a straight 1 1/8" headset. Let's compare two nearest thrust ball bearings from the manufacturer's spec (SKF ): 30x47x11 (dxDxH) and 40x60x13. For 30mm bearing the fatigue load limit Pu=1.6 kN, for 40mm (the nearest to 1,5") Pu=2.32 kN. So the tapered headset can carry more weight or it will work much longer in the same conditions as straight 1 1/8" headset. Additionally, the bigger lower part of headtube allows to increase the downtube diameter and make more stiff front-end. The stiffer front-end gives more precise steering and increases the pedaling efficiency as well.