My father works for a very small agency. His biggest problems are 1. EVERYONE knows a city councilman so you hear the same "I'll get so-and-so to fire you" on just about every arrest 2. His backup could be anywhere up to 15 miles away depending on where the state police units are at the time and if the even smaller town next to him doesn't have any officers that night.
Other lesser things are promotions and assignments. A small department may only have one detective, sgt, name position here, so in order for someone to get the position, they have to wait for the current one to retire.
Medium departments usually encounter the same political BS dealing with city council and people who know them. It's a bit easier to get promotions/assignments because there are more positions, and backup is generally closer
Larger departments usually have plenty of opportunities for promotion/special assignment, usually have less direct political pressure on an individual officer. Backup is usually within a short distance.
Downside is that usually (not all the time however) a large department is in a city meaning the types of calls are more frequent/serious. If you want to be the Barney Fife, walk down main street, check businesses talk to citizens type of officer, a city may not be a good fit.
Pittsburgh Pirates- 1st place NL Central 7/15/11
They've got us surrounded? Good. Now we can fire in any direction, those bastards wont get away this time
An amateur will train until they get it right. A professional will train until they can't get it wrong.