No need on netbooks
Even if you're unlucky enough to get a slow GPRS connection on a dongle, you can still load normal web pages in reasonable time. There's no need for server caching and rewriting (breaking) of web sites to render on a netbook.
The primary reason for slowness on a mobile is down to the speed of the phone itself and the browser, not the network connection. Plus a big reason for content rewriting is to modify for such a small display. Most netbooks have a display sufficient for "full" Internet browsing.
Of course Opera must stand to profit from it somewhere (through advertising or some sneaky analysis of their caches to flog to marketing companies etc).
Personally I still don't trust them for the same reason I don't just MS with IE. It's not open source.
And for a netbook, Chrome is definitely the best browser due to simplicity and maximum real estate (with Safari 4 close behind, though it has some pointless eye candy bolted on).