Magic AB

A simple, powerful reference tool that allows you to switch between the audio you are working on and up to nine tracks in an instant.

The concept behind Magic AB is simplicity itself – an easy-to-use but powerful utility plugin that allows you to compare the realtime audio you are working on with up to nine reference tracks at the click of a mouse.
With A/B referencing playing an essential part in the production, mixing and mastering process, Magic AB offers an infinitely faster, easier and more accurate method to compare multiple audio streams to those currently available in any DAW or audio editor.
Magic AB sits on your mix bus (or individual channels), allowing instant switching between your current project and the reference material in pristine, transparent quality, regardless of the processes already on the mix bus. If required, plugins can be added post Magic AB to provide a sounding-point for programme material with or without additional processing.

 
 
http://www.samplemagic.com/details/184/magic-ab

The concept may be simplicity itself, but its purpose escapes me. Why not just use the Solo button?

I think if you like to reference your tracks against  commercial tracks this is to make it easier.

I know Dave Pensado for one example uses references on each of his projects.

May just be redundant for some but horses for courses I guess.

Yes, reference tracks are very helpful, especially if you work with a wide variety of styles and genres. But I rarely use more than one reference for a given song, and simply click the Solo button when I want to switch between my mix and the reference. SONAR's exclusive solo mode would make it easy to bounce between multiple references. AFAIK, all DAWs support exclusive solo mode (maybe not Logic (?), I dunno 'bout Apple stuff). That's why I'm confused about what this product's benefit is.

same here, not quite sure why you would need this - I do the same as bit - I have my mix and my reference mix set up in a group - one click to switch between the tracks so how could this be easier?
Nigel