I have no doubt that the Q400 will work for SAX in so far as that it will do everything that they want. There are the nuances of these fast turbo-props like turbulence penetration speed of 210KIAS but should do ok for them. Flybe have invested heavily in them and they seem to be confident that they can run them profitably in regional ops as a discounting business model. The long sectors will no doubt errode some of the advantage but the benefits derived from a single fleet may well save them overall
The only thing that irks me as a free marketeer is that these things ain't cheap - $18m+ so has SAX been making the profits to pay for these or is it just one of the perks of being state-owned that you can buy nice new aeries under cut the competition but have no track record of profitability to raise finance on commercial terms. Anyway I'll get off my soap box now.