For me it would a little bit a conflict of interest if the founders will invest a lot. Example, imagine the founders are just CfB and iotatoken. So the Bitcoin-Pott at the very end will get halved. 50% for CfB 50% for iototoken. Imagine now the average joe will invest overall 500 Bitcoin during the sale. And CfB and iototoken just decide to invest 2000 Bitcoin each. So Overall Investment 4500 Bitcoin. CfB and iotatoken will controll 88% of all iota and the Bitcoin they invested the would get anyway back. Possible. So I think it would help if both are quite open about their own investments, because its somehow left pocket right pocket, they dont have really costs, if they throw something in the Bitcoinbasket its anyway theirs.
As for how much I will personally buy: not sure yet, still waiting for the last day of pioneer to make the choice. I treat this choice as completley seperate from the project it self.
Doesn't matter how much of their own token founders buy at an IPO, it is cheating anyway. The more the founders cheat, the greater the impact will be. NXT IPO btw probably was free of that, otherwise their IPO would collect more funds.
It's perfectly OK however if the founders buy their token after the IPO.