I think its important to keep your audience happy.. but you also have to be happy with what you are doing yourself.....How often have you seen a band which is technically brilliant but DULL to watch.
Personally I'd rather watch (and play in) bands that look as though they're having fun... keeps the spark.....
When the fun has gone out of your playing.... and you're just going through the motions, (I feel one of Art's songs coming on **grin**)... it's time to try something new and more challenging, or get some new songs, otherwise you get stale.. and your audience will know it.
slainte
alison