I'd awoken so many monsters via dupes before we got easy access to them in Twinlits. In fact, I'm sitting on 3 max level Siegfried Blue Champions, waiting to be evolved and fed to my Emperor Siegfried. But that would take 4 sets of evo mats (3 to evo to Kings and 1 to ultimate evo to an Emperor). I'm tempted to just eat the time, mats, and exp it took me to raise those 3 Siegfrieds and feed them off for exp, and just use TAMAs to awaken my Emperor. If I continue with the dupe feeding route, I'd be wasting the exp since my Emperor is already max level and max skillled, so I don't need the skill-ups either. I'm sitting on 12 TAMAs and will pick up more this weekend. But for some psychological reason, I hate thinking about "wasting" TAMAs on him since his awakenings aren't even that great. But I wouldn't hesitate to feed him 3 dupes, since they're not useful for anything else. Each of my max Siegfrieds give 78750 exp to same element monster, so about a King's worth of exp for each one. And it took a total of 6 Mystic Masks, 3 Blue Divine Masks, 3 Blue Keepers, and 3 Mythlits to evo them to this point. And it would take an additional 4 Rainbow Keepers, 4 Dub-myths, 3 Dragon Fruit, 3 Mystic Masks, 4 Dub-sapphilits and 1 Dub-rubylit to get the same results as only 3 TAMAs...
Well, after typing all that out and reading it, I'd be an idiot to continue to evolve them all just for awakenings. I guess I'll just consider the mats used on them so far as sunk costs.