The newer k70 has a full sized wrist rest as well as backlit keys. There are also more switch options as opposed to just red. I used to own the K65, it's very great solid keyboard and I'd definitely recommend it. I would have upgraded to the k70 in a heartbeat since it pretty much addresses all the issues I had with the keyboard, but I ended up switching to a topre board since I do more typing than gamming nowadays.
Also, are you getting the compact storm or the full sized one? I actually never heard of the tenkeyless (no keypad) format until a few years ago. I used to think that those compact keyboards were just for people with limited desk space, but being able to have your keyboard a few inches closer to your mouse actually makes it faster and more comfortable to use, so keep that in mind too.