I'm guesstimating that the MAF based PWM valve system used with pure water can see similar performance as non-progressive water+meth or 100% meth. Why? More water = more cooling but we all know that water cannot burn, so if we use a non progressive system with a big jet, the midrange will bog and misfire even though the top end would love it. With a airflow based progressive system the engine won't have to deal with a dump, it can scale it to match airflow.
I don't believe methanol adds that much "octane" to the mixture. I believe it simply cools the charge and cylinder that much better than water because we can use a lot more without misfire.
But all this is just my understanding and opinion. I'd love to see a dyno comparison of the two