The 1000w at 48v claimed with the Ezee kit is power consumption not output.
Typically you can knock 30% off.
I've just checked on the E-bike.ca simulator, they show 700w peak for the Ezee but only 600w for the 408 Crystalyte, both at 48v.
When I got hold of my first batch of Crystalyte motors I went to the trouble of plotting power curves for them, they pretty much matched the makers claims. I did the same with my first SB motor, this was before E-bike.ca's simulator was produced.
Memran if you want to do 20mph forget the 409 it's only good for about 16 flat out, the no load speed is around the 18mph mark at 36v. I haven't got my old graphs and result sheets, I moved office about 10 years ago and I cann't find them. so I'm going from memory a bit.
The 4011 produced 220w peak with over 200w output from 5 to 10 mph.
The 409 produced about 320w peak, with 200w available from around 5 to 12 mph.
The 408 was the surprise it peaked at something like 380w at 13 mph but had 200w from 4 to 20mph,
The SB motor I had was a 20" motor in a 700c wheel it's peak out put was just under 500w at 16 mph, it had 200w from 4 to 20mph, on the same bike with the same battery and tyres it was slower by around 2 mph than the 408 and had a noticeably shorter range, but it seemed to climb shallow hills faster.
If you want to go fast the 409 will disappoint, but even with it's low power it will still boost you up the hills, I have towed my two kids with one up some steep bits without much problem.
With your frame I would recommend putting the battery in a rucksack, below your frame it's going to be a little vulnerable, it works for Steve.