Hi, I have that rifle combination, the Marlin 1894 model in .357 and the S&W 686, I believe. I also have an unusual Marlin, it is the bigger, stronger 336 action in 44 mag; I sold off my S&W 629 some years back because it had been changed out, a cylinder job, which many here can explain, then it shot loose again, so, I sold it and kept the custom hand grip.
I like the idea of the combination, and to be frank, the 357 in the Marlin is quite a nice game getter. As many mentioned, the biggest reason, the 38 Special is less expensive when you buy loaded ammunition and much easier to shoot. I have the 6 inch barrel because I like the balance better than the 4 inch. Someone mentioned a S&W model 10, I had one with the heavy barrel and that was a great shooter; I used them both. Now I would like another 44 mainly because, at my age, I would like showing them more than shooting them.
If I wanted a 44 mag revolver for hunting and lots of practice shooting, I would buy the Ruger Hunter model, which I also had and sold. They are single action and very strong, which is another difference, the gun will last and it is heavy. Most honest men will say that the 44 mag is about the upper limit on good handgun control, while the 357 is more manageable, given a similar weight.
If you are not very experienced with revolvers, or handguns, in general, I think the 44 would be a mistake. You may like the power, but shooting it with full factory loads is tiring. I used to load a lighter 180 grain 44 load with about the same power as the 41 magnum. Some mentioned the 44 Special is not easy to find and they are right.
One reason I like the 44 mag in a rifle is that it has good killing power on deer, at a closer range, as we have here. It is also great for hogs. The 357 is more ideal for close varmints and smaller game. One company, in Georgia, used to sell a little 38 with a 110 grain bullet P+ load and it is ideal for small game in the rifle, while, in my opinion, the 44 is better on deer.
If you are looking for a handy smaller revolver, then get a 357 as unless you are very good with handguns, the recoil is too much in a lighter gun for most folks.
If you like the rifle and handgun combination, you might look for the 357 in a Marlin, I think you will like it.