Very excited to hear that Acqua al 2 has opened up in DC. I've eaten at the Florentine original a number of times and at its San Diego spin-off once while visiting my brother. Frankly, I think the restaurant is stalking my family... but I am happy to have such a delicious stalker. Hopefully, I'll get to our DC branch soon, but I tend to think you are better off using the pasta sampler as a means to identify which of their pastas you like, because some of them could be really good, but some were just mediocre. The star of the menu, though, is the filet in either the balsamic reduction or the blueberry sauce. I started out a firm believer in the superiority of the balsamic and came around over time to recognize the greatness of the blueberry. There's just nothing like it... and I can hardly wait to have it again now that it is in my backyard. (Not literally. That would make for a huge backyard.)
I'll put up a report on how this one compares to the original after I get a little firsthand experience with the new Acqua al 2.