Framework complexity is tricky. If your system is massive enough that you spend 20% less time doing "the framework" than you would have doing the code that the framework replaces, then you're good. But as a project shrinks, it's harder to justify. Sure it's nice for, say, GWT to do a bunch of ajaxy things for you, but for the most part, you can probably hack up the same stuff with dojo and JSP in the same or less time, and forget the extra complexity.
But there is a tipping point, where you invest in some extra complexity at the beginning, take the hit, but then 2 months down the road myriad things are easier and more consistent because of it.
Also think about tool support. Java and JS have good code/debug support, Tapestry less so. How easy is your day-to-day work with the code.