I've finished two projects so far and am working on another with these needles and I love them! Very easy to use, and the locking attachments are the best. I've used other interchageables where the cords come unscrewed. No chance of that happening here.
What can I say? Berroco is one of my favorite yarn producers and Ultra Alpaca Light is fabulous! It's soft and durable and knits up beautifully. I used this yarn held double for a coat/jacket/cardigan and was very pleased with the result, which can be seen on the project page on Ravelry.com: http://ravel.me/ConnieCaps/ec