The primary inherent advantage of an Open Source unit, which is also modular and designed to use common, widely available parts, is that it can be economically maintained over the long term.   All components used are easy to replace and can always be sourced, in the near or distant future, from many different suppliers. 

Because the parts can be sourced from suppliers other than the original manufacturer/designers, the incentive to engage in planned obsolescence is broken.  

Additionally, there is no need for the company to stay around for the very long term in order for the unit to continue operation very long term.  70% of companies in the business of home improvement products are out of business within 10 years, and 50% are gone within only 3 years. 

Long warranties are therefore nearly useless anyway.

It is important that building elements be effectively maintainable over the long term to get a good return on investment.  Buildings are a long-term proposition.

If a unit lasts 30 years instead of 5 years, that means a naive reckoning indicates it's average cost of operation is 1/6th as much, per year.  This has a major impact on return on investment.  The OpenERV has only one wearing part, the bearings, and they can be replaced easily.   The other parts can also be replaced indefinitely.

The use of additive manufacturing and open source components is no philosophical matter.  In order for the custom mechanical components to be easily and economically obtained into the distant future, they are both necessary.  No machine of this kind can be produced without a few custom mechanical parts.  The only practical way to make such custom parts widely available from someone other than the original manufacturer is to use common digital manufacturing processes and publish the digital manufacturing files.

Fortunately, for electronics, the ecosystem for components has a lot of good commodity parts that are widely available.