Yes, already have. If you floor the pedal the modes are all the same speed. However, if you drive 0-60 while keeping it in electric mode (easiest in Econ mode), it is about 4 seconds slower to 60. This is because the battery doesn't provide enough power to max out the electric motor, it requires the extra power from the generator/engine (Genset) combo.
The numbers I got averaged 2 directions on a cold morning (unknown reduction in battery power) were, the i3 was in warmer weather so not totally fair comparison:
Clarity running electric only: 13 sec
Clarity Hybrid Modes (any): 9 sec
Gen 1 Volt EV Only: 10 sec
BMW i3 Rex, EV only: 7.5 sec
This is using Torque Pro! over OBDII, so not using accelerometer. Should be consistent between my individual runs, but the exact number will be different from magazine (they do 0-60 a bit differently, like allowing the car to roll a few feet before starting, etc).
So the Clarity is pretty quick for a 4000 lb sedan. I imagine magazine time would be around 8 seconds, which I think most are. It is a bit faster than my Gen 1 Volt was if the Clarity uses hybrid mode.
Sport mode makes the go pedal much more aggressive and kick on engine easier (even just under brisk acceleration, so watch it

). I much prefer sport mode, but Econ isn't bad, just push the pedal a lot more and it is snappy in that mode too.