I've been using GLXD16 for a couple of years and can't praise it enough, it's an awesome unit - extremely reliable, well-built, convenient to use. The tuner there is one of the best tuners I've used, I still miss it. The bodypack is all steel, also very good. And the battery life is just awesome. Even if you forget to charge it in advance, all you need is a USB-microUSB cable and some USB port for like 15-20 minutes, and it'll last through a show.
I switched to a rackmount GLXD14, just because I wanted to free up my pedalboard and only have one cable running from it to the rack. It's much easier to setup things this way.
With regard to switching guitars, I found that using just one bodypack and plugging it into different guitars is the easiest way.