yes on its own, heck yes if you have a lot of sig stones to pump in.
Yes, don’t put sig stones in him though unless you need prestige
I used my awakening gem on him, and just r5 mine! Mate, no regrets whatsoever! He is just a completly different champ after coming back. As for the sig, its not really useful which makes it even more appealing (unless if for the PI argument people mentioned). The sig just makes the degen to the 30% health slower - I can't think in any specific scenarios where that's super useful - maybe allow you to take 1 extra hit in that period?