As long as both systems are the same voltage, it is probably best to tie them together. Both charge controllers help charge all of the batteries, and both inverters able to pull power from all of the batteries. The more you can share the load, the easier it is on all components. Even if running both inverters hard, the shared current across all of the batteries will be better for all of them. The only advantage I could see of splitting the systems is in case something fails. Maybe have a disconnect switch to isolate the systems. You can tie together as many charge controllers as you need, up to the maximum charge current of the total battery bank. Even if they don't "talk" to each other, they should all be programmed to the same absorb and float voltages, so even if they switch modes a little off time of each other, it should be fine. The only problem you might run into is when you run an equalize charge on lead acid. If one charge controller goes into equalize, you need to be sure the other controllers can handle the higher voltage.Even if the voltage does not hurt them, they may throw and error and shut down.