So you tested the “PID speed control no acceleration”. Be aware that this mode doesn’t make the board legal in Germany. It was only a test and to be prepared if the law get’s changed. And if you want to output 250 watts then you also can add the efficiency loss by calculating 250 / 0.90 = 277 Watts for 90 % efficieny of the brushless.
You should give the normal “Watt no reverse with brake” control also a try.
BTW i run my single drive board with 1600 Watts max and my dual drive with 1200 max Watt each, (so 2400 Watts total).
If you want to compare Watt control against Current control then set the max watt by the this calculation.
Your Max Battery Amps * 3,7V * Battery Cells = Max Watts
E.g 30A * 3,7V * 10S = 1110 Watts
But some more tips for “PID speed control no acceleration”.
You said that you like that it slows down going downhill. I recommend to switch off breaking in cruise control. You can do that over the advanced tab. Because then it is really nice to carve at cruise control.