The DA 40 and 70 is very small and light, fast AF and quickshift. Slower aperture though.
The FA 43 and 77 are a tad bigger and heavier than the DA's, litle slower to AF and no quickshift. But they are faster! And the give very nice bokeh and subject isolation. Thats where the biggest difference is.
Imo the DA's got a modern digital feel and look to them. The FA's got the kinda old look with more character to them. "Pixiedust" they say.... i dont know about that, but they do render beautifull images.
All these lenses are very very sharp and very good!
Good luck
Personaly, i'd go for the FA's