I'd consider a CA G3SG1 instead of the TM. The only thing substantial about a plastic G3 is length.
I assume by secondary, you mean you'll be alternating between carrying your G3 and 416 into the field, not both at the same time...
I'd strongly encourage a more supported platform as your first GBB, something made by TM or clone of TM. P226, maybe. The Maruzen P99 is much harder to locate spares and expertise for in case of a problem, and having your first GBB being unreliable and a headache tends to leave one a bit traumatized towards future GBB purchases.
"The Bird of Hermes is My Name, Eating My Wings to Make Me Tame."