1 big or 2 small canisters on a 200L?

Hello everyone! This is my first post....
I am an Australian but am currently living in beautiful (not) Shanghai.
I have got 4 approx 4.5 inch discus at the moment and hope to add a couple more soon.
Good news is that for a 4 inch good quality Red Melon (?) discus you will pay about AU$7 ea. Crazy cheap huh!
So I've just been given a 200L tank from a generous friend but the existing filter is stuffed.
I'm trying to decide on whether to get 2 x sunsun 302 canisters or 1 x sunsun 303b.
The 302 is rated at 1000l/h and the 303 at 1400/h. Maybe 2 x 303's? What is the general rule for water flow for discus?
The tank will have a thin spread of gravel and driftwood. Pics to come soon.
I can get basic sponge filters here but the look terrible imo.

1 have 2 x 2217 in a 200L tank. Works well with 2 as you have redundancy, and you can take 1 filter per month and give it a really good clean and still have the other operating in the tank.

So if I am running an external inline heater do I just attach it to one of the filter outlets on a 2 filter setup? Or do I need 2 external heaters (one per filter)?

2 2217's would be boss, over kill but great I run a 2028 and 2017s on dads 4x2x18"tall.

if you have the money 2 filters are better than 1, anything with 150l/h real world flow (not rated pump speed would be great).

just stick your external filter on 1 filter.

Cheers guys. I'll see what I can find over here.