I think the problem with Brathwaite right now is that he's not quite Test quality, but he's too good for FC level. Caught in a Phil Hughes-like position at the moment. I can't see a reason why he won't go on to be a very good Test match batsman though - what he's achieved at his age is quite remarkable.
Samuels has always struck me as a guy who makes Test runs in spite of his technique, not because of it. Seems like an all-or-nothing type player; the highs will be extremely high, but when he gets in a rut/isn't 100%/just cbf, he's going to be very mediocre because he doesn't have the technique to fall back on. And based on what I saw of his attitude in the BBL, I'm not entirely certain that he's going to be around the WI setup for a long time before he goes down the Gayle route.
At the moment, only Shiv and Samuels in God Mode are batsmen who would actually strike fear into Test attacks. Against the rest, you feel either like they'll get themselves out inexplicably after making a start, or aren't in the business of taking a game away from you. Darren Bravo is slowly gaining a reputation, thanks to the NZ tour, but there's no feeling of consistent danger from the entirety of the batting line-up. Also the tail starting at 6 was a bit of a problem (though Ramdin has improved out-of-sight with the bat).
From Bahnz's XI, would it be an option to bring in Pollard as VC under Ramdin for a few series, see if he can make it as a batsman bowling a few handy overs, and groom him for captaincy? From the little I saw of him the the CPL, he looked like he had a decent cricketing brain, and his FC record isn't bad (and let's be honest, the competition of Narsingh 'my off spin is more useful' Deonarine or Dwayne 'how long until I break again and only play T20 for two years' Bravo.