I think your current setup is ideal. It's hard to justify when your employer already has an office, though. Even if the company allowed for "100% remote work" it would be nagging at me that I'm choosing to work away from my coworkers. I love what Buffer is doing. When the default choice is to work remote and I can choose to meet my coworkers and work with them in person, it comes off much nicer than having the default choice being working in the company's office.

I think you'd be much more likely to be able to keep the arrangement you have now if you became an employee of a company like this than if you became an employee of a company that had a traditional office.