Werth has been a lead off hitter for all of four months of his career. Bourn has been a leadoff hitter his ENTIRE career. Bourn is considered to be more of the "prototypical" lead-off hitter. He doesn't hit for much power, but has a quick bat and can get on base at a high percentage. The perfect formula for a "prototypical" leadoff guy is to have a guy who sees a lot of pitches, has good speed on the basepaths so he can steal bases or leg out a hit, and gets on base any way possible. This is the "ideal" lead off guy.
Werth gets on base at such a better rate that it negates bourn's basestealing. You could also make a case that Werth is the better baserunner of the two. Werth found his mojo in the leadoff spot and I don't want to mess with that. I'd go with a bernie/moore combo in left until goodwin is ready. If it turns out that moore is a power hitting god, then keep him and we have a great trade piece in goodwin.
RF werth
2B lombo (until rendon is ready)
3B Zimm
CF Harper
1B beast
SS desi
LF Moore/Bernie (until goodwin is ready)
C Ramos
looks solid to me.