I have the flash metering accessory for my Gossen Profisix (essentially the same as the SBC, except in Canada we got the European version) and it works very well.

The case makes a big difference - it protects the button from accidental pressure. The 9 volt battery is so easy to get and (relatively) inexpensive, so it is easy to carry extras.

I have had my Profisix for years, and the ISO and EV adjustments don't slip - in fact they are stiff and sometimes hard to change. It may be that your meter needs a mechanical adjustment.