I'm happy to finally see a full approach post about Synereo, I have been expecting one like yours for the past couple days as all i could see were mentions of the cointelegraph article and other copy pasta. Thank you @dana-edwards!

I learned about Synereo recently and have limited in-depth knowledge about it (will go through the full white paper soon), but I do see it as a very complex, application (smart contract) building layer (indeed, with composability as a main advantage) and off course with full decentralisation etc. etc.
I know Steem(it) has gone through a rough period when it launched due to the need of monetary centralisation for control purposes (main Steem holders are the founders) and since something similar happen to Synereo, that is the main thing that stopped me from buying AMP. It still does. Yet I am reminded of something Elon Musk said on the matter of SpaceX going public and letting shareholders control the path of the company:

From: Elon Musk
Date: June 7, 2013, 12:43:06 AM PDT
To: All [email protected]
Subject: Going Public
Per my recent comments, I am increasingly concerned about SpaceX going public before the Mars transport system is in place. Creating the technology needed to establish life on Mars is and always has been the fundamental goal of SpaceX. If being a public company diminishes that likelihood, then we should not do so until Mars is secure. This is something that I am open to reconsidering, but, given my experiences with Tesla and SolarCity, I am hesitant to foist being public on SpaceX, especially given the long term nature of our mission.

Those last words are the key: "...the long term nature of our mission.". This is why the majority of coin holders is in the hands of the founders, they have the vision and the commitment to fulfill it.

Another point I wanted to mentions is that I think some competition (Steemit vs. Synereo) will only benefit the ecosystem, either platform will improve thus giving us the best to use. The development path is great for both. Steemit is not allowing yet the building of direct apps into the Steem blockchain, Steemit is the only one, but when that happens, who knows what great things will take advantage of the blazing fast transaction processing speed and all other advantages. Synereo has been in the works since before Steemit and some of the devs there are from Ethereum, but let's see it in action, let's see the adoption there and how things are managed when issues happen (like hacks for ex). Steemit has behaved exemplary on this part.

All in all, exciting times are coming for us, both Steemit users and Synereo.
Decent might also be relatively in the same stack even though they are lacking strong dev power.

PS. If you could edit the beginning paragraph of your article to correct the spelling errors that would be great as it might ruin the whole feeling for some :)