They'll defo pump up the insurance, they're always looking for an excuse:mad2:, but to answer the original question any good spring conversion kit should come with an ECU bypass cable to eliminate the fault messages, if you go cheapo and don't get one, they're available on ebay individually.
Personally the EAS is much better when working as it should, far more flexible and ultimately safer, because the car will be at the right height for the situation, particularly relevant at speed because with springs you'll probably find you're centre of gravity permanently raised causing instability at speed:crazy_driver::rolly:.
If you're mechanically able to do the spring conversion, then fixing the EAS shouldn't be beyond you either, it just seems a more daunting task because its outside the norm:5bsmash:.