This is a very well thought out and well-built solution for folks wanting to switch between two instruments.
If one instrument has a hotter signal than the other, you can run it into Input-2 and trim that level to match the softer instrument. You can also passively restore any highs that may have inadvertently gotten bled off. (In practice I found this was an important capability, even with the buffered, low impedance signal from my upright bass.)
Even without powering up the LED indicators, I find this box is easy to use. Construction is rock solid and the foot switches provide good haptic feedback. (That is to say, I can feel and hear the "click" so I don't have to wonder if I really made the change or not...)
This unit is enabling me to do a lot more doubling than I used to. I can fire up the 6-string electric for a few numbers on a Jazz gig or sprinkle in some acoustic bass guitar with the pop band. Swapping goes about as quickly as possible.
I would recommend this v2 version over the older model for the placement of the jacks (all on the back), the placement of the trim knob (up top for easy access) and the option to have indicator lights.
Radial BigShot I/O version 2
True-bypass Instrument Selector