While I'm a huge fan of having an external knife blade, the ST300 wins on simplicity sake. Huge, rugged, no pieces to lose (a major gripe I had with my Surge), and just a very well made heavy-duty tool.
The weight of a MT doesn't bother me as long as I am wearing a belt, which I do as long as the jeans/shorts I'm wearing has loops for such. As mentioned, the ST300 sheath is pretty sturdy and displaces the weight. I often forget about having it unless I need it. I find the tool selection to be just about perfect. Scissors would be nice, but the lack of them is not a deal breaker. I keep my knife sharp enough to do anything that a small set of scissors could do. It's a simple tool, but well thought out and engineered. Everything seems to have a place and every tool has a job. Some get a little miffed about there being 3 flat drivers on it, but I have found each one of the hollow ground tools fit a pretty specific and common screw size.
I think my biggest complaint of the Surge/Wave is that of the 4 that have passed through my hands, ALL of them would jam up if I didn't carefully position the jaws when I went to fold them up. Aggravating when you are fixing something and only have one hand with which to fold the tool and sheath it to get it out of the way. That is one thing I liked about my SOG Powerlock. I could just flip it closed liked a balisong. The ST300 isn't that loose, but I can actually close it against my thigh with a good firm push.
In short: ST300 all the way, for me.