Go for the PhD. It's where your heart is. Otherwise you'll be more likely to regret at least not trying, you'll always wonder what would have happened if you

Go for the PhD. It's where your heart is. Otherwise you'll be more likely to regret at least not trying, you'll always wonder what would have happened if you did. You have plenty of dev experience if it goes wrong to go back into another job. And you can always do it part time?