My primary "feature" would be increasing the server speed. I have several other features, which should be simple to implement, but I begin with requesting a better connection to GC. This is vital for both current and upcoming users that the interface works smooth, continuous and fast which is definitely not the case today.
I sincerely hope this is a planned update in the near future, as I'm already looking for alternatives for my data. I've only had my 405 for two months.
Other suggestions will come later if implementation of current ones (from other users as well) are put into practice.
A fantastic watch though!