The precision adder is a great way to expand sequencers and add or subtract voltages, if nothing is plugged into the inputs every switch adds or subtracts 1volt.
It's a cheap and versatile unit so a definite must own in every modular system.
I cannot think of anything negative about this module.
I already have 2 and I'm going to add one or two more, couldn't live without the 185-2 anymore.