Haven't flown Jetblue but, considered them too.
Their rates were usually one of the best. Then I noticed that most of the connecting flights were very close (ie. 25 min in our case).
Concerned, I e-mailed them and got a very prompt response.
"Thank you for your e-mail. Because all of JetBlue's flights in JFK airport are in terminal 6 you should have no problem connecting flights. As for your baggage concern we will transfer from one JetBlue
flight to another, however we do not transfer to other airlines flights.
Hope all your skies are JetBlue!
Mindy
-JetBlue Customer Commitment Crew"
So, haven't flown with them but like their customer service.