Great blog, combining my two favourite things, music making and technology :-)

Given that you are working on a mostly stable website, have you considered splitting into Scrum and Kanban teams with the Kanban guys managing short term tasks for the web site? The scrum teams still manage longer term projects and could also morph into feature teams if for example you decided to have device specific versions of the site but wanted to have the same features on each.

You could also consider getting into analytics to really guide development, for example using Google metrics to check your sales funnel and common flows around the site to make sure they really do work for the customer.

Then of course you can start looking at “lean” to get really customer focused, you are halfway there in your project definition, you just need to extend it to get business value and costs :-)