Be sure to check that attachments can handle the high flow...anything with a hydraulic motor I have a standard flow 185...off the top of my head, the brush cutter, auger and stump grinder you need different models for to handle the high flow.
I would like to see the high flow stump grinder, my standard flow is decent, but I bet the high flow blows through stumps.
The high flow isnt a constant flow rate. The machine lets you select which mode of flow you wish to run your machine in, normal flow or high flow rate.