Makes perfect sense why the Varios struggles. Do we know this persons head height? The Varios is 2700GPH at only 18ft, and they usually don't push that with all the restrictions with 90 degree angles and if one adds long Vertical and/or Horizonal runs. All measurements are based on straight up shot from the pump. More than likely he has 90 degree connectors and who knows how long his vertical and horizontal runs are.
The Vectra m1 has a head height at 2000GPH is at 21Feet, which is almost double the head height. So this pump is more likely to push the envelope and hit that max where the Octopus struggles. It may be a cheaper alternative for a DC Pump but there is a reason for it.
No offense meant but 21 feet is not twice the height/head of 18 feet. You may want to go back and check Ecotech Marines own head height/GPH chart.
I haven't seen very many people complaining that the Vario S struggles. As a matter of fact, I have seen more people complain of issues with their M1 than I have of the VarioS pumps.