Ask HN: Carta (eShares) for equity compensation, any experience with them?

I have a self funded, profitable business and my first hire, who is also a key hire asked for a co-founder title and equity. The advice I've received on how much equity ranges from 3% to 30%.

A VC friend suggested I create a 409a to come up with a valuation and then I can back into a number for equity. Carta seems to offer this as well as many other useful features for a company that does plan to raise capital.

Any experience with them or any suggestions for a competitor? Bonus for your opinion on how much equity I should give and should I give that title.