I use the V2 to link the clock signal of my drum machine and note input from a midi keyboard, which then splits to a sampler, and a separate sequencer which drives a number of synthesizers.
Pros are - it’s very simple to operate, just plug in two inputs at one end, and feed the combined signal out to one or two outputs. No noticeable lag / dropouts, never “crashes”, good shape/size.
Cons - As other reviewers have said, not all midi sources supply enough voltage to power the unit, so, if you are trying to merge the signals of two midi controllers (a keyboard and a fader-bank sending usb-to-midi clock from your computer, for example), it’s likely that they will not be able to power the V2. if your midi-rig consists of only USB-powered devices, V2 will likely not work.
In this case it would have been helpful to have an additional usb-in socket, who knows, maybe in V3.
Been using this for a bit more than a year, I use “hardware” synths/machines, so I always have one device to drive the power. Very happy with the product, would recommend for anyone who uses hardware. Might need another soon!