Pro Tools Beat Detective is a good tool, but not a full automatic loop maker. It's more like Audiosnap.
And Structure, omg, worked with it for several years and imo also really cumbersome. Btw, Structure is a third party program by Air music and can be bought as a VSTi plugin for Sonar too.
Studio One's Impact is nice and easy, but also very basic and limited.
In Sonar you can also split clips manually very easy and put them on to the matrix by drag & drop. Each row in matrix can be routed to different outputs and you can use any vst fx on them. Very easy to do, but yes, no so powerful like a real drumpad beatmachine as NI Battery or Machine.
Cakewalk could do some features in that area better, but I don't think they want Sonar to be a competitor to NI Machine or Air Transfuser.
Do you want that Sonar become a beat machine, or do you want Sonar should be bundled and sold with a better beatmachine vsti?
I agree, Cakewalk could improve Dropzone or make something easy like Studio One's Impact.
Imo, if you want a real beat slice, mangle, play etc. tool, go and buy a good 3rd party program to do that. That's almost a better option as most DAW bundled plugins.
_Markus