I started PromptWorks with two other senior software engineers with nearly identical experience. Nearly 3 years, 20 staff members, and a few million in revenue later, I can say it's working well.
It's a real advantage to have three interchangeable co-founders. We just divide up the work and since there are three of us, there's never a deadlock. Our pair programming background also gave us a leg up on collaboration and giving and receiving control. In some cases zone defense is necessary, so we carve out areas of responsibility for each. Our experience has been overwhelmingly positive, but perhaps we're just incredibly well matched.