You do realize that Opera Mini 5 is available for both devices.
The flaw on the Blackberry can easily be remedied by software. The flaw on the Nokia cannot.
If you have seen Opera Mini on the BB 9700/9630/8900 at work, its no contest vs. Opera Mini on a QVGA screen. The screen on the BB actually has a higher pixel count than the iPhone, yet its all compressed into a tiny space. Its so sharp at first I could not believe I'm actually reading characters that small.
Another thing is that the BB's are now coming with 256mb of RAM as default, which is an advantage over heavy memory laden pages. I get browser errors on S60 often, primarily because the web page couldn't load. I don't get that even on the slow BB browser.