I think another key point is one that was only partially touched on in this thoughtful post. When you go to raise your B round, this party round A is going to l

I think another key point is one that was only partially touched on in this thoughtful post. When you go to raise your B round, this party round A is going to look "different" than what the B investors are used to seeing. Anything that looks "different" creates some amount of impedance on the deal. B round investors are used to seeing a few familiar names from the A, and at least part of their diligence is based on if they want to work with them or not. This doesn't mean don't do it - it's just another point to consider.