Welcome .kraM! Great to have you on IIS and thanks for the feedback. How did you hear about us?
A lot of people have bought bino's from AOE recently, and I haven't seen any bad reports so I reckon whichever you get will be a winner.
Have you got a tripod to hold them on?
The 11x70's are borderline hand-holdable, and only for short periods. The 15x70's will definitely need a tripod. For astro-observing with binos, there's a lot more to be seen when you can relax and take in the view without your arms shaking or having a wobbly tripod or a sore neck.
Don't forget to read
Binoculars - A Basic Guide for Astronomy, and look at some of the articles and threads for home-built binoculars mounts.