I would definately do an ADC rating if the CAA allowed the self study route (as they used to). It's a huge financial risk for people to leave a job, spend c£20k and not to be guaranteed a job at the end of it - especially with a young family.
The shortage of ATCOs at non NATS units is likely to get far worse as NATS closes the door on issuing ADC ratings to those chopped during the Appr/Radar course.
I've suggested via GATCO that FISOs, (perhaps with several years experience), should be able to either self study, or do a shorterned ADC course. This would provide a new route into the ATC world, provide new ATCOs and attract people to the FISO role - what do others think?