Having spoken to a number of ex SH mates who've gone to the airlines, many find the job desperately boring - the grass isn't always greener! Those who've moved on to rotary jobs various around the world, or in the UK, are generally happier with their lot. I would suggest that in a few years you get your ATPL(H) as a bit of insurance and then see what the outside world is like as you get closer to your exit date.