Has anyone every purchased the Universal PowerPass - the lowest level Universal annual pass?

We will be staying onsite for 1 week and will bounce back-and-forth between the pool and parks. We may venture off to Disney for 1 day, but would like to have the option of visiting Universal more than the 4 days offered by it's "biggest" multi ticket. I will not take advantage of the annual pass discount for the hotels, because we were sent a code for a room discount which is greater than the APH discount.

I understand there are blockout dates for the PowerPass and they are currently listed as follows:

2014 Blockout Dates:
Universal Studios Florida:
January 1 - 3, 2014
April 12 – 25, 2014
June 14 – July 31, 2014
December 19 - 31, 2014

Islands of Adventure:
January 1 - 3, 2014
April 12 – 25, 2014
December 19-31, 2014


All benefits and blockout dates are valid on a calendar year basis and are subject to availability and to change without notice. Not valid for the Hogwarts™ Express during blockout dates.

So, my questions are:

1) The part about the blockout dates being "subject to availability and to change without notice" makes me a little nervous. Currently, we are absolutely fine with the dates we would like to visit. However, does anyone know of Universal ever switching around/changing the previously posted blockout dates for this pass?

2) Has anyone ever upgraded their pass? I'm thinking if I buy this pass only to find out that blackout dates have been added, is is possible to simply upgrade our passes to the next level so blockout dates are not an issue? I would be OK with doing this and just make sure we book next year's trip 1 week earlier (and utilize the APH discount if I wasn't provided a better offer code). I may also meet family down there this November outside of the blockout dates...

Has anyone had any experience with this pass and can speak to how often (if at all) Universal fiddles with these dates?