don't know about immortality, never experienced that. in theory i'd agree with you... too much of the same is boring and becomes torture.
couldn't an existential dread be resolved if we could experience more (all the literature and knowledge available a click away and the technology that allow us more time to spend for our whatever we do - the research done on the human body and mind)... search and find, explore and define, expand our horizon to the point where you could say " (I) am" ? (or find an answer that brings you peace?)