So I give my opinion without having tested the "pedal"
Indeed, when looking on the net, and you realize that a simple switch, stereo jack, an LED and a resistor (or a dozen euros with an aluminum casing) will play exactly the same role, well we feel a little pigeon having to buy it € 70 ...
I have therefore made one, I suggest you do the same, it's very simple.
Note that the "real" favorite switch can also be used on other tap tempo pedal. (But again, perform this kind of installation is so simple ...)
In short, it looks pretty, design sticks with El Cap, but it is 50 times too expensive for what it is!