I don't have either so my comments are mere mind-play, but I once planned on getting a 342PD and was disappointed they dropped it. Since then I can see a couple of advantages to just buying the 340 and using .38s in it. The scandium frame is stronger than the alloy frame of the 342 which might come into play over time if one shoots plus P. (Probably not but, hey, the scandium frame is stronger.) Secondly, the 340 has that little "shield" above the cylinder gap which adds a measure of protection against flame cutting. Disadvantage is slightly more weight and more attention paid to cleaning if one plans on shooting .357s after a lot of .38s. They are darned pricey, though. Both are pretty slick little revolvers.