Ironically, the close-ratio five-speed makes more of a difference the slower you drive.
If you normally blast around all day at 4-5000 rpm, and make most shifts near the redline, you may not need a five-speed. Yeah, you'll get off the line and through the quarter faster with that extra cog, but if that's all you care about, you can probably just juggle the ratios in your four-speed box and accomplish almost the same thing.
It's the rest of the time - when you're just noodling around in the neighborhood, or carving through some twisties, or cruising a fast two-lane with some steep hills, that you start to really appreciate the five-speed.
I think my engine is just about in the middle of the heap as our cars go. A mildly-tuned two-liter set up to have some low-end torque, but to keep its cool here in the land of Dry Heat. It's strong, but not a screamer. It's happiest around 3000 rpm. By 3500, it's starting to work. By 4000, it's tapping me on the shoulder and saying, "Hey, how long are we going to keep this up? I take it to 5000 when I really need to scoot - like merging onto a freeway. It's a blast and comes on strong there, but that's not where I or the motor want to spend most of our time.
Ted rang one of the five-speed bells - that 5-4 downshift is one of the main attractions. You're on the highway, around 55-60, and you come to a hill that's a little too steep for top gear. With my four-speed, I dreaded that downshift to third. Bang, there we were at 4500, and I had a buzz saw in my ear. Now, it's 3800 or 4000, and no big deal. A two-liter will pull up almost any hill in that gear at pretty low speeds with no complaints.
That gear is also my cruising gear of choice on a lot of the foothill roads around here. These were graded for horse-drawn wagons in the Gold Rush - tight turns, and short, steep grades. You're cruising at 35-60 and need short bursts of torque to power through. A freeway gear is just too tall here, but third is too short.
Bottom line is that the car is just a lot quieter when you want it to be with the five-speed. You've got more options. Tear it up or just cruise. You never worry about having the right gear in a Civic or a Corolla. This brings the same kind of ease to a Speedster, even if you don't have a monster in the engine bay.