If you mainly upgrade its weight, set it to wondering and have a rex or something else then you leave it for a while then go back to it, it will have a LOT of fiber and then put that into the rex and repeat, you will never run out of fiber
Possibly the most useful creature to go caving with as his small size but large health and damage allows him to withstand onycs,spiders and scorpions haven't encountered a arthurplura yet so not sure how effective he is against it
These guys SHOULD work similar to a companion in other games. It should be able to wield a sword along with the ability to wear more than just a helmet. Having a tame that acts as a warrior would be very cool for battle in ARK.