Version 6 is coming. Vedder is finishing the new Vesc-tool and should have something for everyone soon. I expect him to make some sort of announcement in the next few weeks.
Version 6 is much more than just switching to direct-fets and a new layout. It will perform on a whole new level and requires some new components which will result in a higher production cost. Simply switching to direct-fets will result in a very small increase in price but adding heatsinks is a requirement. We are considering building these with several different heat sink packages, the most affordable will be what we offer now. Fully enclosed ultra slim options will also be available.
If designed well, a dual drive will perform perfectly with the original v4.12 designed by Vedder and the extra expense of heat sinking and switching to direct-fets is not really needed. We really only see problems when using hub motors due to the huge amperage spikes and efficiencies we see on 1:1 gear ratios and single belt-drives with 2:1 gear ratios.
Adding heatsinks and direct-fets alone might not add much to the constant current handling of the vesc, you will need to provide some sort of active or passive cooling with vents and/or fans to see real gains.