2. Your company is angel-backed. If and when it wants or needs to raise additional funds, is the company obligated to protect said developers from dilution?
Assuming that you're a typical angel-backed company, the answers to these questions are "stock options" and "no." Which would mean that:
1. Your developers don't own anything.
2. Your developers don't have an equity interest (or potential equity interest) that they can trust will actually represent a specific percentage interest in ownership if and when their options are exercised.
I don't mean to pick on you, but your comment highlights two things:
1. Just how loosely the word own[ership] is used when it shouldn't be.
2. How percentages are used to inaccurately describe potential equity stakes when those potential equity stakes cannot be reliably translated into percentage-based (potential) ownership interests.