The mines ARE gonna be a bitch. The only way around them is to walk around them, or shoot from a distance. Yeah, I guess the Mk is better, but I found my own results, not the stats they have for each gun. Sometimes the recoil affects everything, and sometimes the silencers don't do shit for it, sometimes they do.
Also, I found that the heavy vests arent worth the cash. I still took the same amount of bullets with or without one. I think they came into play with grenades, when one goes off nearby.
With the upgrade to a better gun, I wonder if any gun adds will be made. Maybe some better weapons.