Kapton - You'd better take two bottles as when I started flying with them it wasn't the Let410 but the Dornier 228 of FLM and I had no problem flying on that or with FLM either.
As for the choice of Let410 over the Q400, the choice is not made on aircraft type but of the operating carrier. One I'm more than happy to fly with, the other there's no way I'd get on their flights. That's not listening to other people, just decision made on what I have seen. I'll not mention specifics but no problem with either aircraft, I've done many flights on Q400 in both Australia and New Zealand and also worked in Oz for a Q400 operator.