As in title, I think it's overused in LFS. Every self-made, WR, or even standard (!) setups have clutch pack in default. If available. But only UF1 hasn't it.
IMO some cars should be restricted to only viscotic clutch or open diff.
In my feelings simple LSD feels more realistic. Floor gas at corner exit and inner wheel is spinning, then a little punch and everything is ok. With clutch pack there is lack of 'roadie car feeling'. And even in GTRs I change diff to visco, because it is easier for me (mouse) at feels better.
And I don't understand RB4 center diff really. There's percentage slider front/rear, and LSD or open.
How can you operate the torque with open diff?
I will understand clutch pack in center diff, OR just front/rear wheel drive with only visco in center diff.
It doesn't make sense for me now.
IR clutch pack is used only in: Honda Legend, Alfa 147 GT*, Lancer EVO, Subaru Impreza, tuned Mini Cooper 4x4, Enzo.
350Z, BMW M3 and others have visqo or open diff so... what you think?