I think best acoustic is the original acoustic ;] I've got k550i@w610i and i tried to acoustic from w880 and by sunfire7... sunfire7 has got "bad bass", w880 is good but it has to loud high tones.. Now I'm using original acoustic of w610i and it's very good ;D
I have small question - my acoustic files are .zapf but i found some files with .ace or .eac (or something like that :p) on my phone. What is it?
(sorry 4 bad english :D)