I too am doing MUCH better now with SureType. I was ready to throw in the towel a couple of days ago. 3 key concepts have helped me immensely, the first being the most important:
1. Do not make any keystroke mistakes. Once you hit a single wrong key you are absolutely guaranteed to get garbage for that word. Spend the extra time and effort to hit only the correct key every time and immediately correct mistakes when they do happen.
2. Toggle between Suretype and multitap by holding down the "next" key just to the left of the "space" key. It's also possible to toggle to multitap and not realize it, when intending to select words from the list in SureType, and then nothing seems to work correctly.
3. In certain specific fields, like when entering passwords, and when entering "difficult" words, switch immediately to multitap for data entry.
Hope this helps. My accuracy has gone up to about 99%, and my speed is pretty good. Now if my hands will just stop cramping from the tiny keyboard