sure for some problems. but as i said I’m developing externals too, so sometimes they are just not working ‘as expected’ … anyway , i just don’t see why I would try to avoid running PD in graphics mode for testing/dev… its so easy, flexible, useful.
stepping back a bit, I get why not to run the X server during performance, but why are you trying to avoid whilst not in ‘performance mode’ i.e. test/dev? and if you really want a ‘clean environment’ (understandable) why not have a 2 sd cards, one for performance, one for dev?
SC vs PD, I think that’s more down to what your trying to achieve…
I will say, I don’t write much PD code, I tend to prefer writing externals, and then gluing them together in PD… I guess i could do similar in SC, but I didn’t find its handling on live midi input/output as intuitive… but perhaps need to give it more time 
(is there an equivalent to a PD ‘external’ in SC?)