As I understand Miller's motivation, this option would only be for things like developement. THis way you could test some changes to builtin objects without having to recompile Pd all the time.
recompiling pd is something that can be done within one or two minutes ... when you are working on an external and only changing one file, you just have to recompile the file you changed and link the objects ... thanks why there is the make tool ...
Currently we have another problem: That there are 2.5 parallel versions, which are neither older or newer than each other. (Or you could say, that currently Miller's version is the newest, this might change again this weekend. ;)
since i commited miller's changes to the devel_0_37 branch, it is the newest one again ;-)
but you are right ... having two or three branches is not very good for the development... it's not really good if there is one version with development in the dsp core (msp), one with development in the gui (impd) and one with different additions (devel_0_37). basically miller is working on the core, mathieu on the gui, and a few other people like thomas, guenter and me on some other features ... we all agree that miller's branch is the official branch, the language definition. i don't know, if it's useful to have mathieu's and miller's development divided to two different cores... if mathieu is working on one part of the main branch (the gui) and miller on the other part (core), they should work on the same branch. also things like thomas's inlined simd code (which is far better than anything gcc or icc produced, i checked the machine instructions and did some profiling), like guenther's tooltips (which are _very_ useful for to use in abstractions) or my fftw support (more than twice as fast as the mayer-fft, and selectable at compile-time) or threaded soundfiler (which has been reported to work on win, osx and linux) or yves patch for a threaded gui (i have to use it for my performance patch to be click-free)...
and i doubt that we should reinvent the wheel several times by rewriting something that is available in another branch...
cheers ... tim, who is hoping to see one stable branch and one development branch that will be a future stable branch...