For example IPO will collect 500BTC. Devs want money for their previous work, ok 100btc. They want money for current work, ok another 100btc. 300btc will be held for future development (who will control this fund?). I dont understand if they want that every work they will do will be paid, why they want to get such big percent of coins in their hands. It is kind like I (group of investors) hire someone and he will make some product for me. But they will get 15% of coins ( 100 btc at IPO price) more. So they want money for product and want to have this product.
1. We will not get btc for previous work.
2. All btc for future development.
3. Btc will be store on our btc account, all payments will be described (reports every month).
I think if you will raise 500 btc in IPO, 5-7% will be enough for dev team. 400 btc is great amount for future development.