It is nice to have a racing bike off-road for nice days even if you don't race, but a trek 4300 is a hardtail with front suspension & v-brakes, 3 years old makes it a 24 speed right? Properly maintained you can have forever amounts of fun on it. The longer you put it off the greater your joy will be when you eventually get a high end off-road ride. Your skills & stamina will be better able to feel the difference that a race bike can make. You'll feel like you're flying.