The new rendered piece feature is pretty awesome, but I kinda feel it's missing something: the ability to pick which version to show by default. It's not something I see being used often, but nonetheless it's a layer of polish that would be very welcome in some situational situations and rarely occurring occurrences.
One use for it would be in a situation like
[here], where after Bella posted an iterated version as a paintover, afterwards other users convinced her that the original version was better.
I think this option would fit best on the piece options screen. By default the option would have to be on "last submitted version", but allow people to override it and pick another version as the default.
However, this does present a minor usability dilemma when the user would submit another rendered piece after an alternative default has been set. You would have to choose whether this would result in:
1 - the setting remains unchanged. The old default remains. (the drawback being that people could get confused why the rendered piece submission "doesn't work" when they forgot they changed the setting earlier)
2 - the new rendered piece submission resets the default piece setting, meaning it becomes the new default (a rare drawback scenario being the user getting annoyed they have to go to the options every time after adding a rendered piece to revert to the desired one)
3 - a message popping up notifying an alternative default is in effect, and giving the user the option whether to keep or update the current default.
(I would personally recommend option 2 or 3)
Another minor issue to consider is, if you allow the original "session" version to be picked as a default, how to display that on galleries. Displaying it identical to before the rendered versions were added could work, but it would be better to somehow let the viewer another rendered version is also available. Probably with a message similar to the current "(rendered)" for rendered pieces in galleries.
Woo! Another minor feature suggestion that somehow turned into a design document of sorts! :P