Well I have a template file I use when I create buttons that has all the states labelled on separate layers so it's never an issue. The only time I do the 1- trick is when I'm getting graphics from someone else and it's not really a big deal for me. I would be handy to have a flip feature I guess but I don't think it's going to be a deal breaker for most people - especially if they're coming from a Kontakt background
So yeah, it would be just a function for quick preview and setting up the start/end/loop points in the sample editor, so the playback should be separate from any of the modulation/gain/effects of that sampler module - just raw playback of the sample, modified by the settings you set up in the sample editor itself (volume, pan, pitch, loop/xfade).
Oh, another thing: Mouse wheel horizontal zoom to the waveform would be very useful if these workflow conveniences are implemented.