Ive been step mashing from the time I started all grain brewing and have found that you don't need to start out at a low temp like 120 to 114 as you do trash your head retention and body of the brew. Or at least that is what I found to be the case and you don't have to be for that long of a time at the lower temps. Depending on what I'm using like rice or corn I'll start out at around 130 to 135 and only keep it there for about 15 to 20 minuets than kick it up to the next step. If I want a little more ABV or body I'll adjust the heats and time schedule accordingly If your making something like a stout or porter you will most defiantly trash the head and body by starting out below 130. I've tried a few single infusions but just don't like how the end product comes out. Just my taste. I also use a mash out at 168 and have found it improves my efficiency as I think it helps make the surges less viscous so they pull out of the grain bed better. On a porter for instance I will mash in at 135 just to get things started for about 15 minuets and than kick it up to 156 and hold it for full conversion than mash out at 168 for 10 minuets and than batch sparge. I end up with an ABV between 5 and 6 % and a good foamy head that slowly drops down to a nice thick lace around the glass, good body and flavor profile. With out the Mash out my efficiency drops form 82% to 76% so it defiantly helps out.