This (record button latch to transpose) has been long requested. But I doubt very much that it will ever happen.
As for panning in Unison mode, it does work. But when only 1 voice is selected, that will always be voice card number 1 (the synth will always use voice #1 at first, which is panned pretty much near center). If you use more than 1 voice, with the Pan Spread knob to the max, you will get stacked panned voices.