I ALWAYS step mash. It is very easy on my system. For me it is all about controlling the BODY of the final product. Yes I do make dry beers, but I also make very rich full bodied beers (from very simple grain bills)
A step mash will only give you a dry beer if you mash for a longer time at B-amylase rest temps. I always to a rest at 147 F (64 C) and then a rest at 160 F (71 C). I vary the times to tailor the body. If I want dry, I'll do 30 min. at 147 F (15 at 160). If I want full bodied, I'll do only 15-20 min. at 147F, and then 25-30 min. at 160F. I like this approach over a single infusion as I can create a fairly fermentable wort that still has some longer unfermentable dextrins in it to provide body. This allows me to keep my drier beers from being too thin, and my richer beers from being too heavy.
These time are what works on MY system. The times may vary depending on how quickly or slowly you can ramp between the temperatures.
I don't think there is a big influence on flavor either way, except for how flavor is influenced by the body of the beer.