I, too have had no success with any of the multitude of soft keyboard options out there. They all install, and I have the options to turn them on and select them as input method, but the soft keyboards just never show up.
The one I just tried was Utlra and it may have given me a clue - it said that it couldn't bring up the soft keyboard while the physical keyboard was active. Since the Pro doesn't have a way of disabling the physical keyboard, perhaps all the soft keyboards are misinterpreting this and assuming they shouldn't show the soft keyboard. Don't know if there's any solution to that...
...Alex