Which target audience did you have in mind?
Primarily Doctor/Nurse/Practitioner centric?
Primarily Administrative (Practice-as-a-whole) centric?
Insurance centric/integrated with insurance systems/standards?
The trickiest part about it all that I've found, is that at the end of the day, practitioners tend to only need a few pages or so worth of notes, but most modern, proprietary alternatives tend to morph into gigantic, data vacuums actually intended for somebody's (generally an insurance company's) data analytics department.
Which don't get me wrong; I realize that was the point behind EHR; greater interoperability and communicability of health records between disparate systems.
For most proprietary offerings, I believe the value is that your vendor whips up and manages the data model and infrastructure for you (or offers a reasonable template); and will typically integrate some sort of rules engine because why not.
To be honest though, I'd absolutely love to figure out how to implement a suite of tools to make EHR easy for practitioners, plus maybe an application with sufficient and accessible enough documentation so that a sufficiently savvy practitioner would be able to out of the box basically have a good digital SOAP note-book, and could overtime build up the data they want to track in a logical, but user (not necessarily developer friendly) manner.
Basically, something as accessible as making a .dot template for printing out, or filling out blank SOAP notes forms for entry in a binder, but also having enough back-end where if need be, that data can have ETL's cobbled together for migration. Plus all the HIPAA goodness.
Unfortunately; I don't know as the market would see much uptake in the U.S. since the insurance industry kind of wags the rest of the medical industry's data collection practices due to how tightly integrated/dependent the healthcare industry is with the health insurance industry.
The centralization increases visibility of a lot of problems; however, everyone pays the price with requirements implication chain becoming longer than the amount of wire between you and the insurer.