Zero-Turn Lawn Mowers

I am in the market for a zero turn lawn mower and looking for advice. I want a mower that will last a long time and allow me to get the job done quickly so I can spend time with my family on the lake. My needs are as follows:

1 acre
20 trees
50-52" cut
might pick up a few yards for some extra cash including my church which is about 1.5 acres
$6000 max

Brands I am considering:
eXmark
Gravley
Cub Cadet

I looked at eXmark last year but didnt pull the trigger. I saw a used one that was 52" w/ Kawasaki motor 4 years old w/ 1200hrs for $3000. That seems like alot of hours to me but it is half price from new? Thanks in advance!