I have a Preymaster and it's a solid unit. However they have a newer model with built in speaker that is smaller and easier to carry. That remote speaker on the Preymaster is another thing to carry around. I put mine on a snap-link and hook the speaker to my fanny pack or back pack for quick and easy deployment when I move into a stand. Less movement that way.
To be honest though, about half the time I leave it behind and just carry my mouth calls, which always go with me regardless of whether I have the Preymaster or not.
series are good callers too, but more expensive.
The most use I get from a Preymaster is locating coyotes with howling. The howling sound on my card is very good and saves me from blowing my guts out as much. Once in a stand though, I prefer mouth calls. In heavy wind the electronic is nice, but I rarely hunt in that much wind anyway.
I can't knock electronic calls, I own one and use it. But they are an investment, and more to lug around. Here in CO, alot of my hunting requires me to park in a designated area and walk long distances, so that caller gets to be noticable.
If you don't mind dropping the change on it, and don't mind carrying it around the field, they are nice luxuries to have.
Lastly- I have called more songdogs to mouth calls than the electronic. That could be due to any number of factors of course, but I've just noticed better success with mouth calls.