In reply to JohnBson:
I'm currently working towards MIA after doing the training last june. It has been a lifestyle choice and I'm lucky to live in a place that allows me to get out when I can and I have a wife who supports me financially as she's the breadwinner.
I am a qualified teacher but I only work on supply basis though this does pay quite well and through the summer I use my ML award for mountain hikes and DofE work and I have a good balance here as winter tends to be busy for teaching (lots of illness over winter!) and during the summer there's lots of DofE work and people wanting to climb snowdon.
Honestly, how much you can earn is dependent on how much time you can devote to marketing yourself, finding a niche and how far you are willing to travel for the next job. My realistic expectation when I qualify (hopefully this year) is that I won't start earning significantly more than I am currently because of the MIA - The ML will always earn more unless you're really lucky.
My advice would be to go for it if you think you can make it work, but don't expect it all to happen quickly - I thought it would be a quick transistion but once you do the training you realise how much you don't know and need to spend time perfecting before assessment.