I bought a scorpion on the recommendation of Paddy SP - must be nearly 10 years ago, its my 'go with' every time out with TI and the Archer.
I have found that at this time of the year the best calls are vole squeak and young rat in distress. At other times the snowshoe hare is a favourite - wont bring cubs in but always an inquisitive adult.
As with any equipment the secret is learning how to get the best out of it - ie what call to use and when, how long to play it and what volume to use - even down to what angle from the muzzle to set it up and to disguise its appearance.
Beware of tawny owls pecking it when on vole or rat squeak!!