Yes. New array 2S3P (2 panels in series, 3 sets in parallel)
On the 1200W array, if you're saying you have them 2 in series and then 3 sets of two in parallel (Voc= 90.42), then you're definitely good. According to this page:
Specs/datasheet: AS-5M-200W solar panel made by Worldwide Energy and Manufacturing (Amerisolar) has 200 watt output power with module efficiency 15.7% .
www.posharp.com
They have a Voc coefficient of -0.33%/°C meaning they are MORE sensitive to temperature than the new ones, BUT they have more margin to start with at 135.63Voc. They are good in 3S down to about -7°C. You might find a slight performance improvement in reconfiguring to 3S2P provided -7°C not a risk in your area.
The panels are not sufficiently compatible to consider mixing them on the same controller. You would take a performance hit greater than anything you would gain by reducing the utilization of the second 150/85.
Good to know about the linking. I'm only familiar with the newer Smartsolar units, and I think they dropped the CAN interface in favor of bluetooth and VE.Direct.
Lastly, your battery...
12X Gel 220Ah 12V @ 48V?
If you have 4 in series for 48V, and you have 3 strings, then you have a 660Ah 48V bank.
If that's the case, you want to limit your peak charge current to 10-15% of your C rating, i.e., 66-99A
6000W/48V = 125A at very low SoC
6000W/57.6V = 104A at absorption voltage
If you tend to get fully charged early in the morning well before peak solar, then this is not a huge concern.
You should check the following:
1) Your battery specification permits a charge current this high. Gel batteries are typically a little lower than FLA/AGM, but that varies.
2) Your battery bank is wired to optimize and equalize the load between strings (link #2 in my signature "Wiring").