Hi!
At Last some one else is having the same issues. I thought I was starting to lose the will with our Webasto heating system.... We are having the same problems and to date over the last month had to replace the Glow-pin, gasket, the burner its self and now the Burner tube this is after we had the system declooked and cleaned out. It ran okay for about a week and then just stopped working and 'just died of death'. We too have been in touch with BK Marine who supplied this to our new boat via The New Boat Co, and amongst other marines all said the same in relation to the system not agreeing to the use of Red Diesel so I strongly agree with your findings.
Are you able to let me know which heating system you have replaced the webasto with. Im not sure how much we can take with it as it never seems to improve.