Currently I’m trying your list out since I have all the cards, but instead of 2 thoughtscour im using 2 lava spike to make the deck that slightly more aggressive..

I would consider adding in a 23rd land. I think thunderous wrath is a good idea but perhaps just a little bit cute. I would prefer a more solid instant in that slot, like the 4th cryptic. Maybe also add electrolyze as it has incredible value when flashed back.

Are you familiar with Turbo Xerox theory?
http://bopmtg-bopmtg.rhcloud.com/blog/turbo-xerox-rule

This deck has 16 cantrips that cost two mana or less.

In terms of raw mana, you’re right—you need to flash back a spell with CMC 5+ to make Gearhulk more mana-efficient than Snapcaster. But you’re underestimating its 5/6 body, which puts a ton of pressure on opponents, and the pertinence of flash in combat. Dropping Gearhulk and blocking a Siege Rhino, all while flashing back another spell, actually nets you an additional 4 mana since you’re eating that threat for free.

As for acceleration, I don’t think it’s necessary if you pack enough disruption. Disrupting and acceleration (example: IoK and Hierarch) serve the same purpose in midrange decks: they bring the game to a state in which we can cast our higher-curve spells. 6 is a lot, but Blue Moon has been known to make plays like Snapcaster-Cryptic. But it’s certainly possible the deck needs more disruption or some acceleration to reliably make it to Gearhulk territory.

1. Reunion doesn’t put you down on cards when it cycles spare Revelers. The Reveler puts you down one for each additional Reveler it discards.

2. Yes.

3. Yes.

It’s not the same. If you end up discarding a Reveler to casting another one, the first Reveler was a dead card you never got to use. When you discard it to Reunion, you trade it for another card that you can use, and then eventually play the second Reveler when you have no cards in hand.

Oh one more. If it were the case that more cycling was the answer, why no prior lists using tormenting voice? Is the extra dig and discard by one card that significant?

2. Along the same lines, you also concluded that reactive spells and reveler don’t play well together. Given that your above list runs multiple reactive spells and a reveler playset, how does reunion fix this problem? Is simply doubling up on cycling tools enough to mitigate these tensions?

I didn’t know we could run 6 drops in modern with 22 land. Especially without ramp.

But apart from that, these look like spicy. I agree that Grow provides a more robust experience, as many tri-color decks do.

Im not too sure about Torrential Gearhulk.