Speaking from my personal experience, the most valuable thing I seemed to gain when we went from from one person to two is companionship. Having two people on b

Speaking from my personal experience, the most valuable thing I seemed to gain when we went from from one person to two is companionship. Having two people on board made it much easier to keep up the momentum, because I now didn't have as much need to put down work to hangout with my friends; I was already working with a friend! I've found that separating out the technology and business concerns (at least in the companies that I've worked at) leads to, occasionally, bad solutions, tension, and a lot of the creativity is squelched. Sometimes, good ideas look uninspired from merely a business perspective, uninteresting from a technical perspective, but in reality they're great ideas. A good example is the DOS licensing deal. Making a CP/M compatible operating system (poorly) isn't that bright. And from their business perspective, IBM couldn't see it's platform being commoditized, because they failed to understand how portable software would become. But Bill Gates understood.