For range use or just keeping at home?
4506
For actually carrying around?
4566TSW
I'd sooner desire to carry a 4563TSW, though.
I carried an issued 4566TSW for a while, and I soon traded it in for an alloy compact weapon (since I was carrying it for a plainclothes assignment).
I know guys who are carrying 4566TSW's for plainclothes, and the weight becomes a "not uncommon" observation from folks wearing them for 8-12+ hours at a time.
I finished my career carrying a 4513TSW, which gave me only 1 rounds less magazine capacity. Not everyone may shoot the alloy compacts as well as the all-steel 4566TSW's, though. I've seen my fair share of folks who simply shot the heavier 4566TSW's better than the 4513TSW's, even though standard pressure ammo was being used. Just depends.
The heavier weight of the 4506 would make for a nice range experience.
Your safe wouldn't care which one was resting on the shelf.
As far as some parts are concerned, the older 4506/4566's might have less easily obtained barrels available at some point than the TSW's. The 4566 barrels are not the same as the 4566TSW barrels (like the 4006 barrels are not the same as the 4006TSW barrels). Last time I looked at some new production 4566TSW's and had called back to discuss some barrel questions with S&W, they were still making some revisions within the 4566TSW line.
I had a couple of 4566TSW's in front of me one day, made only about a year apart, and both had differently machined barrels (and a couple of the machining differences were easily noticeable). The barrels would work in either TSW, as I was told the newer changes were simply some design & machining improvements the engineers had incorporated. (This was something like 4 years ago.)
The 4506 (and its later revisions) are pretty well known and respected as real workhorses among the folks who like to own and shoot full-size 5" .45 pistols. Heavy, but that helps make for an enjoyable shooting experience ... until your arms and shoulders start to fatigue.
