For me, the question that the startup should ask more critically is around the total dilution-to-exit. If taking Paul's money for 6% now reduces the dilution at some subsequent round from, say, 40% to 30%, then by my reckoning the founders end up with 66% instead of 60% of the final position. Key here is usually a combination of the value-add from the VC, and their ability to underwrite/cornerstone a good part of that follow-on round. (Although obviously this is only relevant if a larger follow-on round is going to be needed!)