chan_ss7 or libss7 for production system?

Hi I am unsing Asterisk 1.8. Now I have to attached SS7 ITU ISUP E1.

Please guide me should I use libss7 or chan_ss7 ?
Is libss7 is now stable enough to use in production system? with expected 180 concurrent calls ?
Is there any version of chan_ss7 for asterisk 1.8 ?

(I am not interested to install asterisk 1.6)