I've generally leaned toward the school of thought that the leadership is sincere, but probably the two biggest things that make me doubt their sincerity are the overlapping generation teaching and the allowance of blood fractions. What these teachings have in common is a seeming refusal to admit that they could be flat-out wrong about something they previously said.
Instead of admitting "We don't know how long a generation is", they've come up with a new definition of "generation" which strains logic in order to explain why we're all still here in 2014. Interestingly, though, they did admit indirectly in 1995 that they didn't know the length of the "generation" when they defined it as basically an "era". Then they debuted the crazy "overlapping" interpretation in 2010 which goes back to making an assertion that they definitely know how long the generation is. But they were almost humble there!... on this one issue... for a period of 15 years.
With blood, the general agreement among us is that they allowed fractions because they realized that the Biblical argument for not taking blood was weak, and they may have had concerns about coming under attack for the loss of life that the doctrine was causing. But instead of just dropping the doctrine, which could have opened them up to massive lawsuits over lost lives in the past, they said that some parts of blood could now be transfused -- if a Witness' conscience allowed it! Since JWs have been programmed strongly to be repulsed by blood, that means some JWs would still turn down a transfusion even now.
It's worth pointing out that this "conscience matter" line that they used for blood fractions was also used when the organ transplant ban was lifted. Back then in 1980, long before the current GB, there was a similar refusal to acknowledge that they had caused needless deaths, and a similar refusal to admit that there was nothing in the Bible forbidding organ transplants. Instead of saying, "It's actually totally okay to get a transplant", they weaseled out of the need to admit fault by saying that transplants were now a conscience matter!
One could say that these three examples demonstrate a lack of sincerity, but there's still an alternative way to look at this, which is that the enormity of the mistakes over blood transfusions and organ transplants were too great for the leadership to contemplate. It's a well-known psychological response to shift the blame away from oneself when one seems to be responsible for something really bad. On top of that, when it was previous leadership that was responsible for instituting the policy, it's easier for the subsequent leaders to shirk the need to apologize since "it's not our mistake".
However, at the very least, this attitude indicates a lot of pride, or in fact I would say hubris, at the organizational level. They are too full of themselves to be willing to lose face by admitting wrong. And that's not very Christian for a group of men who are supposed to be closer to Christ than all of us "other sheep".
