Obviously it will be dependent on a number of factors for each individual.
I'm on £44k at a job that is basically fine, but after a series of very crap days a few weeks ago, I applied for another job which I now have an interview for. It's the same level but should be more like 50-52k.
Is that enough of a difference to leave a job which is basically fine? Pension, benefits etc would be similar.
The new job is more aligned with my interests, but potentially less scope to develop skills - particularly line management which I do currently but wouldn't do in the new job.
I don't even particularly like managing people but feel I would be cutting off the opportunity to move up further if I'm not doing it.
This is all a bit counting chickens before they hatch but would be interested to know if there's a minimum % you think it's worth leaving for and any other pearls of wisdom.