Would have preferred a system like this, combined the random system with a progression based one:
Make mecisto mantle no longer a wearable cape, add a player stat called 'CP Bonus'.
1st Turn in your best CP cape (+48%) to set your base stat, requires all KI+megaboss KI of any content level.
NPC sets your CP bonus stat is now +48.00%
2nd and all capes after the 1st add 1/100th onto your existing base rate
Turn in another cape (+27%),
NPC increases your CP bonus stat to +48.27% (+0.27% not 27% since it is not 1st cape turnin)
Now all 'cp capes' are useful and worth something, you get incremental progression and getting lucky on augment is still worth something.
Would give incursion more longevity and nq coffers more worthwhile to spam opening.
They could then make that CP bonus stat cap out at +100% or whatever.
*The 1st step setting the base CP bonus stat could also be repeated by an NPC menu option, if somehow you previously had a lower rate like +30% due to bad cape luck.
This would let someone who later gets a +50% cape to 'upgrade' their base rate past their current best.