Spine, Gov's got a good point. If you do not intend to shoot .357s, a 642 makes a lot of sense, as does a 442, and you may still be able to find some new ones without the IL, if that bothers you.
As to the 15-oz. weight, yes, you can notice the difference between one of those and 340PD in your pocket, but not really in a holster. Lots of guys who worry about aluminum frames carry steel-framed guns (much heavier) in their pockets and get along just fine. The weight difference is not really a deal breaker on the 442/642, IMHO. I have both 442 and 340 and use them interchangably.
My initial comment was not meant to discourage you. If it was indeed not very "helpful," sorry for that! The two pieces are day and night, in my mind, thus your question led me to believe it might not be entirely serious - as we sometimes see when a troll shows up just trying to start a fight.
My apologies, and good luck with your decision. Both guns are U.S.-made by companies who have a reputation of standing behind their products. Either way, you will be OK.