Hi!
In principle it sounds good but the surface plants would need to be buffed to compensate. At present the advantage of underground farming is that you can do it immediately since you get the seeds on embark. Surface farming needs a skilled herbalist and time before you get your seeds. That and at present there's more you can do with underground plants (compensated for there being more variety in overground plants and the seasonal nature).
O.o
You know, I am not quite sure whether we are talking about the same game there. As I mentioned several times across the forums, I am a die-hard surface farmer, and I have to admit that I approach that happy-go-lucky: My embarking dwarves have various skills, all at NOVICE level, including one or two novice herbalists. I simply designate an area for plant collecting right together with my lumber designation and at the same time build three or four 2x2 farm plots.
A little while later, I check on the farms if I can plant any plants that are directly edible, and if so have each farm specialize on one plant.
After that, I basically forget about the farming altogether, and I never had any problems with too little produce (my only problems were when I forgot to brew some of the plants and ran out of drinks, but the farming becomes efficient very quickly).
So, I can't really say I ever experienced any of the hardships/problems you are describing for surface plants.
Psieye: Well, I am personally fine with the way things are, but I wanted to voice my support for
Sinistar before the shooting begins :) :) :)
Deathworks