I have successfully meshed gears using a Cam connection in Mechanism. You have to define the two gear surfaces contiguously, and then make sure you check off the 'Enable Liftoff' button in the definition.
Why use cam connection if gear connection itself is available. So far I know cams in Pro/E Mechanisms are used in real life cam connections, tyre on a road, geneva mechanism, and in other intermittent motion uses.
You may use it for gears but ...
Anyhow it depends on person to person and skill level.
The gear connection does maintain the ratio and actually meshes the gears without interference. I have created a wiper mechanism in Wildfire which has two gears meshed. If you are interested I can send it to you.