Im also confused, why is it dangerous to run them separately?
I figure as long as the drains are high enough in the DT it won't be a problem. When I built a 400g with dual 75g sumps, I drilled my drains a couple inches too low and could only load the 75s to 9-10" to avoid flooding if a clog occurred. Like I said as long as the e-drains are going to both sumps and there's enough room in the sumps it should be adequate.
