I think whether the switch should occur will depend on your riding style. The 7300 is a fine bike, and after 3 years should be in fine shape.
The Insight looks to be more in that fitness/road realm whereas the 7300, is more of a trail/comfort bike. The Insight drops the adjustable stem and the suspension forks and seatpost. Component levels are about the same but I am not overly familiar with the lower end Shimano and SRAM lines. I think the Tiagra on the Insight might be a step up from the C102/SRAM-7 combo on the 7300.
It looks like a similar bike in the Trek line would be the FX series.
I don't think the change is worth it unless the Fitness type bikes are more your style.
Thank you for your comment, masiman. I actually prefer more comfortable ride, rather than stiff/fitness ride. Adjustable stem, suspension fork and comfortable seat come quite handy now that that I think of it. I guess I'll stick with my Trek, considering I only put few hundred miles on it over the last 3 years.