Agency prices on the Glock and the 320 are comparable. Most Agencies around here going SIG are doing so because they previously issued classic SIGs and/or they have a chief or range master who hates Glocks.
Speaking of minimal training there are a couple agencies near me whose only training is one day per year during which they shoot the state minimum 50 round qual course twice. A whole 100 rounds per year. Both use Glock 40s.