Here's what I have understood from the factory about updates to the Sinar Hy6 bodies (Johannes may correct me if I am mistaken): If you are an owner of a Sinar branded body and back, DHW is not going to leave you stranded and it may be possible to have your Sinar Hy6 updated to Mod2 specifications and have it work with Sinar backs. It's true for any Hy6 camera irregardless of naming, Rolleiflex, Sinar, or AFi, that some of the oldest were not able to be updated at all - so its always best to check with the factory. I hope to have a ledger of serial ranges that can be updated soon so I can help determine upgrade eligibility. Anyhow, in that case of an updated Sinar Hy6 body, the Sinar backs will still operate. However Sinar backs are no longer officially supported on the Mod2 bodies meaning you can't buy a new Mod2 body and new Sinar back and make them work - without a sync cable. You can of course still by Hy6 bodies and mount new Sinar backs. Hope that isn't too confusing. And for the sake of completeness, Sinar backs can also be fit to the older 6008AF cameras too.
All the Hy6 cameras of course can be service and repaired by DHW ... They tell me they can even service SL66 cameras from the 1960's.