Playing something difficult and impressive but properly rehearsed is one thing, playing something you've just learned and that isn't ready yet is another.

Recently I tentatively planned to play a tune I haven't previously done as a solo, but had misgivings because it wasn't practised to the "foolproof"* stage - and I was relieved when there wasn't time for it.

On the other hand, we've sometime done tune sets in front of a festival or club audience where I was making up arrangements/harmonies as we went along - but that's on fairly simple material that we've done a lot in regular sessions.

*by which I don't necessarily mean that I'll play it perfectly in performance, but that if it goes wrong I'll be able to recover smoothly.