I have a 5906 slide/barrel assy on my 915, it works just fine ! I also have the 915 slide/barrel assy on my 6906, both shoot just fine.
I like the dual tone look of the pistols.
I'm looking to buy a 915 mostly to get the alloy frame. I'll probably go with a 3.5" barrel and slide to give it the SSV look as I did with my 5906 by adding a slide from a 3914: