I've never worked on the 30HE - they're an average boiler, average price and will do the job - if you find a good engineer that doesn't charge the earth for repairs then you shouldn't have a problem.
I have never recommended Ideal and would always recommend Baxi, Potterton, Worcester or Vaillant. That's because I work on those a fair bit- so if you find someone that works for Ideal or works on Ideal boilers alot - they'll probably recommend them.
It all comes down to what installers are used to - they get familiar with manufacturers and certain boilers, how they work, common faults etc etc.
Hopefully someone on here that has an Ideal or works on ideal can recommend or advise against them.