As stated correctly above, it's a trade off. Both are cool. But to date, you can't have both.
You trade off what I call "inlane swoosh" which you get with solid flipper frames when the ball comes screaming in from the playfield to the flippers at max speed -- for "super fun outlanes"
In my book, the best inlane action is Barracora, since the playfield entry to the inlanes is wide open (the opposite of most EMs and Whirlwind)
And in my book, the best outlanes are Viking, since it's fun to often get the ball back into play, and not worry about the outlanes too much. Centaur is good -- but the return rate is very low on my machine (it depends on where the posts are located, and the twist/flatness of the playfield) -- BUT when you reduce risk on the outlanes, you have to increase risk down the middle, which means wider GAP -- (see BALLY 80's games) -- which means FEWER slap-saves, and I'd say that slap saves are near the top of my list for what makes pinball great.
So... If someone could invent a situation where there is no trade-off among all three variables... That would be innovative and magical. I don't think it's happening.
The only other compromise would be to have ONE outlane save on one side...
I think it's safe to say they will never come back. Ghostbusters already experimented with a wider flipper gap, and reminded us how much we don't like that. Ever. But we accept it in older games.
RIP: saveable outlanes forever. bye bye: Trading "inlane swoosh" AND "fun slap-saves" for "fun outlanes" is a no-brainer bad trade. Idea: DOA.