Umbral Fibre or Adaptation for Chroma?

Basically the title. This is only for Profit Taker. I have been using the standard strength/duration build, but I am in the process of minmaxing all of my frames and was curious about this.

Currently I am using Adaptation and I works a charm, but that extra strength might be fun.

Anyone ever tested this? I do not want to use more umbral formas on him if it is not necessary.

NOTE: I am aware that Adaptation will allow you to stack Vex Armour a little faster, but that is really nitpicking...