KLM is a plus and hopefully will be more reliable than flymaybe. People are forgetting that KLM have code shared on BE's AMS flight for a while now so the world wide connections have always been available. This is nothing new.
In terms of the sun routes for them to work you need a 737/a319 sized plane and no restrictions. SOU need to pull their finger out and spend some money airside. Wishful thinking though.