This feature is available in some cheat clients.

That is still not a reason to add even more such features.

Tweakeroo is not meant or developed for PvP or minigames or cheating/hacking/whatever. It's developed as a utility mod for "regular players" and also in particular it has some features mainly developed for (or mainly useful for) technical minecraft players. Like you mentioned it already has a number of features that are kind of "out of the line" and generally considered too cheaty, and I may be moving some of those out of the base mod into a separate extension mod.

Tweakeroo already gives a big advantage over other players. This mod is already on the forbidden list on some servers. There is no turning back.

Oh, ok.

Cool idea but that makes the player with tweakaroo have an unfair advantage over other players.

Tweakeroo is already at the borderline to a hacked client with all those features. but it just isn't a hacked client. I wouldn't push this mod farther into and probably over the border.
This is just too much