Well they may be very happy, but they would be a lot happier on a jet, even a 146. The Q400 is anything but quiet, it vibrates and the noise it does make is an annoying turboprop throb that is far more intrusive than the sibilant sound a jet (any jet) makes.
The Q400 might be cheap to run, but that is its only attribute. The surveys that are done to establish customer satisfaction are very easy to manipulate- If I want to go to Milan, a turboprop is better than nothing, so of course I will be happy.
The Q400 might be OK for short routes, but it is a nightmare for sectors over an hour (I've done a few on it). Hopefully an over-concentration on a turboprop that nobody else wants will not turn out to be a big mistake...