You'll get a lot of different opinions on this. Mine is that the step-mashing (infusion or direct heat) will produce comparible results (based on my own experience doing decoction and step for the same beer recipe). In theory, decoction mashing can produce a higher quality wort, but in practice the apparent benefits may not outweigh the extra effort. You will, however, most likely get a higher efficiency with decoction mashing.
Whether infusion mashing or decoction mashing for lagers, one must still be careful of the step temperatures with modern malts. Protein rests are usually right out, unless done for a very short duration or at the temperature range that straddles proteolytic enzymes and beta amylase. The best thing to do is to know and understand the malt analysis, if available.