It sounds like you and I have a very similar typing style.

Looks like you want a JD40 with an alternate bottom row. With a 3.5-unit spacebar. Keep an eye on my twitter feed for possible updates to the JD40. But don't expect 3.5u spacebar support to be added any time soon. I am liking the layout options I included on the JD45, and I usually like to leave support for larger, standard sized spacebar that you actually have hope of purchasing some day.
