I've had the Shubb Axys Reversible Guitar Slide for a few years.  I bought it because I was looking for a slide that would allow me to switch back and forth between playing slide and playing chords or a lead part that I couldn't do with a normal slide.  This looked like the perfect slide, as this is exactly what the reversible side is for.  However, I could never get it to work quite as I wanted it to.  While it would work sometimes, other times I would find that I couldn't really spin it around quick enough for when I wanted one slide or another.  I also found it a bit harder to play slide guitar when it was on the proper side, as I didn't always feel comfortable with it on.  Perhaps that with a bit more practice I would be able to get the hang of it, but at this point I would rather just play with a normal slide and switch when I want to.  This would only really be useful for live shows and I don't find myself needing to switch too often during a show anyway.  Inside the studio I can do it easy enough without something like this.  While I do think that this is a very good idea, I think it would help if the slide part itself was a bit more rounded to make it easier to play with.  I wouldn't be surprised if others could get used to this quicker and more easily than I could, but the slide just didn't work for me.  The price of the Shubb Axys Reversible Guitar Slide is just a bit more than a normal bronze slide, so it isn't like I spent too much money on this.  I would definitely encourage those interested to try it out first if at all possible, but if not and you think it might be able to help you for switching between slide and non-slide parts, I'd take the chance and check it out anyway.