should I replace both hydraulic tensioners, timing &balance shafts when replacing all pulleys and water pump and both belts?
I would do it all since it’s nine years old and your in there any way.
I agree with @knfenimore. Chances they fail before you’re ready to sell or trade are high. It’s cheaper and easier to do it now.
As a general rule you replace everything. The reason is that you do not want to have a timing belt failure because of a part that you did not change. Make sure the oil seals get replaced as well for the same reason.
Be sure to follow the balance shaft alignment procedure in the service manual or the engine will shake at 2000 rpm when you are all done.