The argument as I understand it is that all your patches apply to 0.42-5. So pick the simplest feature or bugfix you've implemented and submit it as a patch for 0.43. If you get feedback and/or it gets merged, end of discouragement. If you don't, then the development process is broken and needs fixing.
If I knew how I'd do it myself.
Even if I had the time to do this (meaning learn 0.43 code base), it is not that simple. I actually prefer 0.42.5 over 0.43 for several reasons:
as such it is IMHO not production ready. In due time this will change but AFAIK 0.43 is not there yet.
they are for the lack of a better word a hack, a temporary fix if you like until something better comes around to replace aging Tcl/Tk.
thing to a different toolkit as all tcl/tk stuff is encapsulated into one (albeit ugly) big file. As such, I see it as a better springboard for such a transition.
FWIW, I did some digging through the Juce platform and it is rather amazing. I will dig a bit more to see how quickly one could port the core Pd. I also understand that this process will undoubtedly require a huge rewrite of all gui-based externals but sometimes one simply has to take a fews steps back to start leaping forward.
Just my 1-cents worth...
Ico