[GRASSLIST:2592] Integrate erosion model in GRASS

Dear Grass Users,
I'm starting a research about erosion modelling at basin scale.....
I'm interested about grass modules working about this... (swat, answers,
agnps, r.sim.sediment... ecc).
I would whant to use them into grass 5x...
I would want to know if someone of you used them or has some experience about
someone of them... and which module is better for scientific application (it
is not an older version or a not upgraded one...)
I have tried to see how to install the grass/swat interface but I found
problems to understand where to find it... and also with answer and agnps i
have got problems about compiling modules...
thank you very much

Pierluigi