Just recomplied rtpengine with your latest commit.
Indeed it seems to be handling non-rfc-compliant host priorities much better.
D/libpjsip( 8663): a=candidate:Sc0a80104 1 UDP 1862270975 85.xx.xx.xx 4025 typ srflx raddr 192.168.1.4 rport 4025
D/libpjsip( 8663): a=candidate:Hc0a80104 1 UDP 1694498815 192.168.1.4 4025 typ host
D/libpjsip( 8663): a=candidate:Sc0a80104 2 UDP 1862270974 85.xx.xx.xx 4006 typ srflx raddr 192.168.1.4 rport 4006
D/libpjsip( 8663): a=candidate:Hc0a80104 2 UDP 1694498814 192.168.1.4 4006 typ host
D/libpjsip( 8663): a=sendrecv
D/libpjsip( 8663): a=rtcp:30009
D/libpjsip( 8663): a=candidate:Pi2sMxReBtxalHXF 1 UDP 1694498559 190.xx.xx.xx 30008 typ host
D/libpjsip( 8663): a=candidate:Pi2sMxReBtxalHXF 2 UDP 1694498558 190.xx.xx.xx 30009 typ host
Thanks for such a quick response.