Viking have been going for many years now and with the major fleet renewal i can only imagine that financially they are healthy.
The connections between management and xl etc are no secret to the industry.
Viking also have a seperate operation called Viking Hellas which is the greek operation based out of Athens and Heraklion i believe. Viking have had a base out of HER since pretty much the beginning.
Kiss Flights, are basically the new Freedom Flights which went down when xl went but they are now in their second year of operation and personally, never had a problem with them, infact, i wish more companies were as nice and accommodating as they are.
So far, so good and i see no reason why Viking / Kiss can't be sucessful here in the UK. They have major contracts with numerous tour operators.