Note, I don't believe the Arm SAM3X8E that the DUE uses supports floating point, so you are still using an emulator. As others have said, since the DUE has a faster clock rate and is a 32-bit processor, means the floating point emulation should be faster. Note, Arduino floating point uses 32-bit values for float, double, and long double, while I believe the Arm boards use 64 bit. This means the mantissa and exponent ranges are higher.
The recently released Teensy 3.0 uses a Cortex M4 board that also does not support floating point. There is a varient of the Cortex M4 (M4F) that does have floating point, but the Teensy 3.0 doesn't use it.
The Raspberry Pi does support hardware floating point, and runs at a much higher clock rate (700Mhz), so it should have much better floating point. The higher clock rate also means a higher current draw, so you will need to think about more batteries and recharging for long running aps. However, at present, it is more setup to run Linux than to run embedded devices, though I'm sure people are working on it.
I don't recall off hand whether beaglebone or mbed support floating point or not.