The easy answer is that you should continue to learn and become comfortable on your Synapse with Speedplay pedals recreationally, but that you should simply ride your Trek hybrid for commuting and in traffic. You don't need special pedals for the Trek - use what you have.

Is the Trek set up for what you'll really need as a bike commuter? This leads to the standard questions about how much and what type of gear you must carry back and forth, and how you'll handle rain/wet roads, locking and securing, etc. How far is your planned commute?