I have not been a big fan of solids, and it is certain that pressure fed liquid boosters would have been better for the shuttle. The solid manufacturers lobbied hard to use solids instead of the Saturn 5 for Apollo - but the solids "lacked abort modes". That said -

For the CEV, the CEV would sit on top with an escape tower to pull it away from ATK's launcher if anything went wrong. My guess is the launcher would have to be equipped with more sensors then are used by the SRBs, in order to detect abort situations.

The shuttle buffeting may be the result of aerodynamic forces on the stack, rather than of combustion oscillations. I dont' know, but this is going to have to be known. ATK cliams lower g forces with their solid compared to liquids, I don't see any reason why this should not be a correct estimate.

Sweetest combustion I ever watched a movie of was of the Titans used with Gemini - perfect diamond patterns in the exhaust, and a real smooth ignition. Problem was that hypergolics were really toxic, and liable to explosions. Along these lines, the aluminum in solids may act as a catalyst in freon's of the ozone, and this may be a show stopper for ATK. It will be interesting to observe how ozone depletion reacted to the Columbia stand down - if it reduced, then it is likely that aluminum is playing the role of a catalyst in the reaction.

In any case, some kind of backup CEV launch system (in other words, a liquid fueled one) is likely to be desired in case any problem is discovered with the ATK launcher, but this probably depends on funding and initial test runs.

I doubt if Griffin is dumb enough to go to the hill with a wired architecture, so my guess is that the July 18 presentation that "Scoop" is writing about over at nasawatch is likely to be an initial presentation, with a final presentation to Congress due in September. I suspect that a "B team" from Boeing/Lock-Mart is very hard at work right now, with full access to Griffin and his full cooperation.