I've yet to collect my multiple copies of Launcher and Archfiend. For now, even with a sub-optimal configuration, an Infernity deck is perfectly viable till Platinum. It struggles against certain archetypes though (Cyber Dragon and Dark Magician above all) : I don't think we'll ever see an Infernity deck reach KOG (at most, you'll be able to climb through Platinum).
No, I built it and it is a let down; when pulling off the combo you get some crazy boards sadly that "when" almost never happens any backrow and is over damn even Aromages have a field day with Infernity. Thanks god I pulled all the Weather stuff that decks does feel like it'll be tiered.
The deck is a rogue deck. In other words, it is KoG worthy, but it is not as consistent/powerful as tiered decks.
Anyway, if you like the archetype, just build it. If you only try to build decks if they become meta, you'll just be part of that mindless rave that plagues the ladder, not to mention all your decks will end up crippled by a banlist sooner.