I've had the Tippmann Prolite for close to 8 years - never had a single problem with it - only needed to overhaul it twice, if that and it was just to replace the trigger spring and lube'r up.
Upgraded to the A5 this past March. The A5 uses a lot more air then my prolite - and of course you go through more rounds with the automatic option b/c i've got a response trigger.
Bottom line - I love the A5 - its like my own Thompson SMG.
HOWEVER - when it comes to reliability - I CANNOT beat my Prolite. I've been backed in the corner so many times with that - at long ranges with a decent barrel - forget about it. (For non-New York'ers - that means it ****ing rules, owns, you cannot beat it).
Wolf
P.S.
I've got some kickin video at Skirmish USA in a 300 person assault - if someones got some space i'll send it to u and post it up