I think the question is of a more general manner. Would you entrust tasks of very high importance to a SaaS? It's a question of availability and reliability. A company could start with one part of the process. It can gain trust and add more features. At the end there will be the whole package available. It should be possible for the client, though, to only use parts of the package, if they want to keep some independence.
In this particular case I was wondering about the build process specifically. But my root concern is what you highlight, it's a very core process which can really grind a company to a standstill if it fails.
Also I am wondering whether something fully integrated offers sufficient value or whether home assembled systems are superior in people's minds.
