I wouldn't go out without one, its just another tool, that you can use to your advantage, i just wish another company would make them, instead of Deben having the whole market, the mark 3 does have its good points, but that f*****g screeching, which sounds like a cross between Hawkwind and Startreck, They say they consulted Ferreter's, on what they wanted, so I wonder whos idea was for that,
Regarding putting tape over the box to mask the sound, you shouldn't need to.
I have the mark 3, but still prefer the tick tick of my old mark 1s.
Cant understand why no other company has gave it a go,