I've never found a $79 controller that will handle 16kw peak. I've also never run a HubMonster at 40kw. 30kw is the max I've used and never more the 17kw peak input without cooling mods. If you run much more than 100A per controller battery side, then you need to watch the heat. With my ventilated cooling approach I run at 150A/controller without any temperature worries, but I do have mountains to contend with and if I want to run hard to show up motos I don't want to have to worry about heat. Getting to max power is all about getting to a high enough voltage, because there's no getting around current limits, but rpm limits are still unexplored by anyone.
Get the motor out of the wheel, so you can gear it down, along with a pair of truly high voltage controllers, and then 40-50kw is perfectly reasonable with a ventilated motor that has centrifugal blades on the exhaust side. It would take over 200V for iron core losses to get to 1000W. While I wouldn't want to cruise continuously at that rpm and heat generation with my simple cooling, out of the wheel with some ducting and a filter on the intake, it's reasonable, especially since Miles' spreadsheet predicts 96% efficiency while making 127Nm of torque at 200V at 244A. HubMonster will actually do a bit better than his spreadsheet predicts, as I erred on the conservative side with my measurements, which others have proven with their own slightly better measurements. That was with cheapie controllers, and I'm seeing improved range with my PV controllers pushing one of my HubMonsters, so sine wave means true limits are higher do to improved efficiency.