I've heard something similar as well. That they did not want to turn up for problems once the jobs was finished. Then again, I heard very good stories about them as well.
It is true I suppose that in general you can get better (after)service and extra services like plumbing, electricity and tiling from smaller kitchen companies. Especially when spaces, corners etc. are awkward. Then again, if you are handy yourself, Panel Centre and Newman Noyek are grand places. Kitchen companies buy from them anyway.
I wouldn't know if Nolans is a particular good one, but I heard some good about them. You can always shop around further.