i have a 09 sti hatch and had a 07 sti sedan. I moved with my 09 hatch and fit all kinds of things in that massive trunk especially with the seats down. I was never the type to buy based on trunk space but i fit a 50 inch tv and a small fridge in there easily. Costco/ikea/home depot trips are easy i cant believe i just typed that!
You will love the sti hatch.