There's no hard cap. A soft cap exists simply because there are only three sources of Magic Absorption. For non-Bretons, that cap is 80% (Atronach stone + perk). Breton's with the Atronach stone can temporarily hit 100% with Dragonskin.
This. That's what I knew but I just wanted to confirm with others.
I'd rather not use spell absorbtion as it's kinda bugged right now.
Many of your own spells, mostly of the conjuration school afaik, are blocked by it because the game considers them as hostile.
I hope a patch will fix this...
I was aware of the Conjuration spells being absorbed but summons was not something I was dabbling in. Unfortunately, it also absorbs the Quick Reflexes perk from the Blocking tree, something I was not aware of until I did some extensive testing and narrowed it down to Spell Absorption.
Magicka Absoption is "also all or nothing"; so if you're playing on a difficulty where Magic Resistance is necessary for survival, Absorption isn't a viable alternative to Resist Magicka unless you're OK with huge unpredictable spikes of incoming damage.
The way I see it as is that Spell Absorption is another layer of protection. It's definitely very viable in my opinion.