html5 application cache joomla website

[frontenddev]

we build multiple websites for our clients based on a Joomla installation we have customised.

We have to support back to ie7 but I would like to start making these websites available offline. Do people think this is a good idea seeing as this is not an application?

Also how do people feel this would work with content that would be changing on a semi regular basis?

I welcome your thoughts?

Thanks