For me to develop my scripts it would help alot if my interactive shell supports the syntax as well. I mean you are right of course, I CAN do that, but it then becomes a tradeoff question again of whether this non-compatible interactive shell has sufficient niceties.

I agree with you. Have you tried Fish? I find it to be the perfect balance of these goals. It has lots of niceties, which for me was already enough to switch to it years ago. But lately, they’ve been adding lots of bash compatibility, which has made it even more awesome.