Fall Back to Opera 9 on P835

I found my Asus P835 was not flashed to the latest firmware and flashed it. All reset to factory setting and I have to install everything again.
This time I gave the built-in Opera 9 a in-depth testing and found that it was customized by Asus to suit this device, especially the trackball operation. I prefer it to the downloaded Opera 10, so I keep it.
This time I hacked the soft button of Anytime Launcher to launch the Task Manager (taskmgr.exe) though.
I have tried this device for a full week and finished the testing and customization. I would like to stop changing it and start testing the stability.