I think your decision to only back businesses with a technical co-founder is wise. In Consulting and Freelancing for Tech. businesses one pattern I have noticed is that startups with a technical founder who is very involved in developing the product often have a better organised, performant and bug-free product that is easier to build on and extend. Technical co-founders go the extra-mile to ensure things are done right for the long-term because they have to bear the consequences.
Rare to find hired developers that sweat over details of a product whose future is uncertain and they have no stake in. They get paid regardless and can always change jobs before the consequences of a badly built product start crashing in.
The horrors of inheriting a badly built product and being responsible for dealing with months/years of bad decisions and poor implementation can also drive hired developers to quit instead of having to be the one to fix all that.
