As the CMIO of our hospital, I am kept apprised of the upgrade process, timelines and downtimes.
To say that it is transparent to the end user would be an attempt to sell you a bridge in New York.
We have transitioned from pure SaaS to more control locally, but remain at the mercy of upgrade and downtime schedules that are driven by the corporate vendor. They have to consider other customers needs accross several time zones. .
The are upsides as well as down sides, to this model, so it become an individual decision.
A change from local server to hosted by vendor occured with the hospital dialysis facility. Now that became a real pain in the butt, because we had been able to query the SQL server directly to get QA data, now we have to stand in line and pay for the vendor to get us CSV data files.
Personally, I chose AC in part because it my my network and my server, and avoided the eCW penetration here because the most cost effective offering (but 10x the cost of AC) because it was SaaS type.