Hydration: I've ridden with a full 1 liter bladder and it does pull on the shoulders but I only rode for an hour and had no problems. I suspect many hours may feel burdened but will have to wait until summer to test. Also I used the 1liter Platypus which worked and fit better than my camelback reserviors
Nibbi: I've ridden twice and once in hard rain and the other in light rain and didn't experience any leaks. But I will be very interested to hear what your dealer finds. Also I use Goretex and eVent jacket and pants for hiking in rain and I often treat them with waterproof replenishing chemicals to maintain and improve their performance. I will be curious how long the waterproofing lasts on this Klim suit.