I'm pretty sure that the slide on the Trailside is some sort of alloy, but I assume that the frame is steel, since the barrel and frame are machined from the same piece of metal. I got a Trailside about a year and a half ago. Overall I like it, but it's not as nice as it could be. The trigger on mine is about 3.5 to 4 lbs, which is a decent weight, but it's quite mushy. The accuracy is indeed impressive (at least the factory test target). Reliability is acceptable, but my pistol is very finicky. The sights are rather coarse for a target gun, but the integral scope rail is there if you prefer to mount a scope or red dot sight. I don't shoot my Trailside much anymore since I got a S&W 617. I really hate to go searching for the empty cases that a semiauto spits all over the place, but I guess I'm weird that way. Disassembly of the Trailside is a piece of cake. There's one screw to take out, but it's easy. I wish someone would make a set of walnut or rosewood grips for this pistol. The plastic grips it comes with are really cheesy. I like the shape and feel, but the fit is pretty poor. I know you can get wooden competition-style grips, or tacky blue laminated ones, but I can't find any that are plain old wood.
Good luck making your decision!
Dan