For what it's worth the MYT DC10-30 (G-BYDA) has been extremely serviceable this year. I'm reliably informed it has had no B defects for months (except for the Electronic Tech Log). It served very well last winter and is also very busy just now doing Orlandos and Curacaos having practically no delays. Can't comment on the above comparison with the A300 as I know nothing of this type but you are maybe making a mistake to suggest that the DC10 would necessarily be less reliable. Admittedly, MYT did have reliability issues with their three shorthaul DC10-10s which were withdrawn last October but these were very different aircraft and quite frankly they just weren't looked after properly. Not sure how relevant the availability of type rated crews is though as Scandic will presumably want to convert their own crews anyway. If they do need DC10 crews then there are some excellent people about to become unemployed who would be happy to take the job on (and have a lot of partying in the process but that's another story).
Of course an MD11 would be a better aircraft but the DC10 can be leased for practically nothing which is from where the real money can be made (assuming the it's operated by a competent airline of course.)