need help with my system! bio balls? all forums are split on issue!? high nitrate

You have a year old setup that is working so relax a bit.
Stress from worry causes all kinds of health problems. Your tank apparently isn't too stressed.

There is a reason the forums are split on the issue of bio balls. One of which is technology moves on. Another reason is some of the new filtration techniques are simply more efficient than older tech. Better? Maybe.
Another is that manufacturers are encouraging people to buy the latest product. Can you consider that some of the proponents of change, may not have paid money for their new media?

BioBalls were the best thing going, a few years and decades ago. They still work.
Are there better products on the market now? Yes.
Will they benefit your tank and filter? Maybe.
Is your Nitrate a bit high? Maybe. It more depends on how consistent it is or if its declining rather than going up over time. A marine environment is different from a freshwater environment for those fresh water folks thinking you have to bring it down NOW. A water change will drop it faster than anything else.

The bacteria we rely on for detoxifying our tanks live on every surface of the tank environment. Every surface, Every pore, every micro crevice. At least up until the micro pores and crevices get clogged.
That's why people stopped using lava rock when Bio balls hit the market. The pores get clogged. Sintered glass will eventually clog too by the way, but you can bake and burn a lot of that gunk out of glass media.
If you wish to replace your bio balls, do so a little at a time. Don't pull the entire batch if there is any place for you to start seeding the new media.

As for your Nitrate levels, there are products with chemicals to help. There are also anerobic "filter" solutions that can deal with it. The mechanical solutions are essentially a very long black tube that the water slowly flows through. It forms a breeding environment for anaerobic bacteria which eat up the Nitrate.

A simpler solution is to put a light over part of your filter or a refuge box and cultivate some of the useful "seaweeds" in it. But that would be really old technology. With no patents.

I would definitely consider swapping out the bio balls for LR. It also would be a good idea to put some macro algae in to aid in reducing the nitrate. Water changes are the fastest way to reduce nitrates and avoid using chemicals if possible.

If by Poly-Filter you mean The Poly Bio Marine Inc. Poly-Filter, then my answer is going to be Maybe. Poly-Filter is capable of adsorbing a lot of things from the water. It can pull Nitrate and copper and ammonia, but it doesn't sound like you need it at present.

If you mean a sheet of polyester filter floss then the answer is that it should be on top of the bio balls to catch and trap particulates before the water gets to the bio balls. Usually this would go right under your spray bar or perforated tray.

Add more live rock and start removing the bioballs a few at a time over the course of a few weeks. You have enough live rock that you don't need the biological activity on the balls. Move the nitrogen cycle to the live rock and you'll have less nitrates.

If it were me the BB's would be gone BUT seeing as you have had them for a while I would remove a handful or two along with your WC's until they are gone. 50 lbs of good LR in the volume of water you have is fine and you mentioned adding a bit more. That wet dry should be clean and flowing. You will be hard pressed to bring those nitrates down if you leave them. You can add some LR to the wet dry if you want but I would not add rubble but rather good size pieces of rock that you can pull out easily and shake in your WC buckets now and then.

I would have a little filter floss/pad above the LR and change it out weekly (minimum). Do you have a skimmer? If so I would save your money on the Poly-Filter and only use it when you need it to polish. If you don't have a skimmer I would probably continue to use the PF.

Are your fish aggressive eaters?