Sorry to intrude late, but I get your logic.
I've had a dozen S&W .357 but the one that rings right is the 4" .38/44 heavy-duty, the spiritual progenitor of the 520. Everything you need, nothing you don't. I liked it better than my 3.5" 27 (and I LOVE that gun).
I loaded HV rounds with 11gr of 2400 to get it up to semi-.357 performance like intended. It has made me want a 520 once I shot it a lot, other .357s, and figured it all out. Alas, 520s were always pricey but now are getting unobtainably. kudos to you!
Unfortunately mine's a 5" and the 4" is preferable to me, but rare. Love to find a 4" of either.
38/44 daddy pics:
View attachment 903790