The best soft keyboard for mobile devices in Windows CE days, was TenGO. This was a T9 type, predictive type-ahead keyboard, however, it provided for two alpha-buttons on each keyboard row, see illustration. To type you simply entered the word by pressing one of the three six alpha-buttons, and the predictive type-ahead engine did a really cool job of figuring out the word you wanted to enter. If it was not in the dictionary, you could select the actual letter in the alpha block, by pressing the soft key the number of times the position of the character represented I the block. For example if you wanted to enter the character ‘d’ outside of the predictive type-ahead engine, you would press the ‘asdfg’ block three times. Once a new word was entered it went in to the user dictionary and was available to the T9 engine at the next entry of that word.
I hope that the maker of this keyboard, will resurrect it now, not only on iOS but for Windows and Android mobile devices. It was awesome. TenGO are you listening?