Solar Arrays

Hi,
I do enjoy reading answers to questions provided by experienced people who know what they are talking about and share their knowledge.
So I do declare myself as a novice but through lots of research and the help of experienced people have assembled an off grid system that has been running fine for two years but I do have a question to pose but first will describe my set up whether it leaves a lot to be desired or not.
I have 6 arrays (not big by any standard but my thought were redundancies being in a cyclone risk area) of solar panels each comprising 6 panels by 330 watts and each array is connected to its own Victron 150/100 solar controller.
There two battery banks which service different circuits and each battery bank is associated with 3 arrays and 3 solar controllers all running in 12 volt mode but capable of 48v.
Each set of three solar controllers are synchronised as a primary and two slaves for each battery bank.  
I live in an area that has a lot of light all year around and each of the three controllers work really well in together producing around1400 watts max per controller or as needed and automatically adjusted as needed on demand.
I believe this is normal for a 12 volt battery setup with that type of controller.
Here is my question
I am in the process of upgrading 1 battery bank to a 800ah 48 volt system (comprising 4 by 400ah batteries in a series by 2 and paralleling them to make up the 800ah.
Probably wrong with a lot of this but from what I have researched each Victron Controller would be capable of handling around 5000 watts and I know the current array set up could not produce that unless I join at least two in parallel to maybe get around max 4000 output under ideal conditions. I am doing the upgrade to 1 battery bank because I will be upping the load on that bank.
So what, if any, is the right way to combine the two arrays.
1/ at the solar panel array level on the roof in parallel or
2/ at the solar controller PV input level on the actual controller.
Each array is individually wired to separate controllers at the moment.

I am sure I have probably asked a stupid question here lol