I was like there is an AC500, but it's actually the AC110.. or at least that's what I read... with buying all of that filteration.. your looking at spending somewhere from 350-400.. when you can get an FX5 on ebay for around $210 and it should be suffice.. depends on your stock, but it's a powerful machine.. I image it would take a lot for it not to be enough....
Definitely FX5. I have had mine since they first came out and the only thing that has stopped it from running is the power going out. Definitely better than HOBs.
I personally keep air stones in all my tanks for a number of reasons, but one is so that if the filter does stop for some reason (equipment does fail) the water is still moving and well aerated.
The only thing I would do on a tank that large other than the FX5 would be a small pond filter so I have a backwash option.