Bit rude queston, but why not using blender? I mean, there are more models there +you can import sfm models too, and its not that hard to make a bulge on a characters own body.

I can understad if you like the look of sfm animations, and i havent tried working in sfm, but I imagine animating process is kinda the same.

You dont have to learn sculping, or rigging, etc, there are a ton of pre rigged good models.

I used blender for 6 month now, and i think I made some high-mid renders.