Bloodtinge/bloodletter build advice

Hey all just coming back to the game again and curious about some more niche aspects of a bloodtinge build:

First off which aspect of bloodletter is considered the best? What are some fights or situations where it’s transformed version shines above the chikage, especially since I don’t want to boost str past 14?

Is madaras whistle worth using or is it just kinda a novelty once you have the bloodtinge weapons?

On the chikage, are viscerals with 25 skill still good damage or once bloodtinge is 50+ will I be better off just going ham with melee on staggered foes and the skill points are effectively wasted?

Lastly I know damage falls off a cliff after 50 but if I’m not completely lashed to the meta is it worth going past 50 at all? Or are the gains so miserable I might as well level vit or end for more effective dps?

Thanks for any feedback!