Both me and my brother got A5's as our first markers, always worked well and even today after several years my brother still uses his.
The games at warped big game run for several hours at a time, you can refill air at the insertion points but I've always found I run out of paint before I've run out of air (I shoot an ego 11 with 68/4500) I only really tend to carry 7 pods out with me as anymore just tires you out and you end up needing a break just as tommikka said.
You might find running the a5 from a remote line better for big game as you will be carrying it around with you all day and they aren't light little things haha.
Hope this helps you out a bit!
Elliot