You sound pretty clued up mate. And your objections and observations ares simply what went round all of our minds at one time. We couldn't reconcile the mental gymnastics in our mind so somehow we ended up leaving entirely. Some by fading, others like myself, just one day didn't go back.
Despite people wanting to meet with me I strongly told people that I didn't want to discuss my thoughts as it was 1 - my right. & 2 - it saved me feeling like I was 'offending' their beliefs.
This worked. Although admitedly, my cong left off pursuing me to any great leangh due to my wife telling them my position on matters (she was/is still active).
You must do whatever you feel is right. I'd strongly advise against da'ing yourself. It gives people the perfect opportunity to simply dismiss you as a sinner. Though if it'd came down to it I'd have rather done that than be d/f'd.
Just don't rush anything. Keep your cool. Speak with respect whenever you can.
Don't give people the oportunity to speak ill of you due to losing your cool or saying stuff that you may later regret.
And always remember, you've done absolutely nothing wrong. You simply disagree with the religion you were brought up in.
Best
J