I am of the understanding that the GEN:
Straight C3 Lume
Tantalum midcase (brushed) and Tantalum (polished) bezel and CG
On the rep:
Ti brushed midcase
SS Polished Bezel
Polished SS CG
There is no SS on the Gen from what I am told and given the density of Tantalum, the reason the rep will not weigh the same (Ti is lighter than Tantalum)
Just posted a new shot of my 172 in the Friday wrist check - It has Ziggy lume, Chief Single AR crystal and Gen crown. Also oxidized the Ti midcase. and Jimmy Bluehands
One of the nicest Marina designs IMO