[calmon]

Gems are very important in late game. Nevertheless normally you can't 'swim enough' in gold. A nation with very good non-capital mages and lots of castles build 20-30 national mages a turn in late game.

Growth is clearly an middle/late game invest but there also possibilies to improve your early game too.

However what i mean to say is that death 3 is good but its not a no-brainer.
The nearly no-brainer for me is sloth 3
I would always go for sloth 3 before death 3 with most of the nations (even the resource haevy nations, just build a good combat pretender here).