Let the hive mind of Engadget get that for you.
"I just switched to Sprint from Verizon about three months ago for the Pre. Then I went for the Hero about a week ago. Now, I miss my hardware keyboard and am thinking about switching to the Moment. I am still able to switch back to Verizon if I want and get the Droid when it arrives. Should I just trade up to the Moment when it comes out, see if I like it, and if not switch to the Droid? Or something else entirely? Help!"
you don't even need Mandarin or Cantonese characters--they also have pinyin, the alphabetized version of their words. All they would need would be our alphabet and / - \ U symbols to put over certain letters to show pronounciation--it would be much easier than searching through hundreds of thousands of characters. There are so many characters that the majority of people, even upper class, well educated people, don't know most of the characters, only a small percentage, maybe like 10-15% of them. Pinyin would be MUCH easier to do in this case. They all know it anyway, they start our learning pinyin before the characters.
Only problem is that natives don't actually learn romanization (at least in HK, why would they need to?), so any romanized input is going to be less popular than handwriting or something desktop-estabilished, say ChangJie.