I guess my experience with this machine is just different because I feel like I have really good control when using it, even with the angle guides. I've also never had more steel taken off than I wanted. I follow the directions and only use it on low-medium speed though.I recommend the grinding attachment bc it allows you more control over sharpening. With the standard it's real way to tear thru some steel, especially with the course belts.
Truth is I still may end up getting the attachment at some point for its versatility as you said. But so far this thing has been nothing but awesome for my knives the way it is now. I'll try to get some pictures up of some of my mirrors and cutting tests this weekend.