As a new guy I spent a considerable amount of time researching this very issue. My post history will show a few shallow threads asking the same question as the op. I'll save you a diatribe about dogma and simply say that in the end I found concrete evidence supporting the superiority of one design over another insufficient. As a result, I decided to buy pipes in a 1mm intervals from 16mm to 24mm in width.
Smoking Best Brown Flake as a baseline (hard work, but someone has to do it) I found that generally bowls 19mm and below tend to highlight the higher notes while those 20mm and wider highlight the lower notes. What does that really mean? A narrow pipe will make the grassy, citric notes more prominent while a wider bowl dulls those flavors while sharpening the milk chocolate, malty, bready flavors.
I've conducted the same tasting series with FVF, Union Square, Golden Cake, St James Flake, Triple Play and Hal o' the Wynd and have found the results to be consistent. If you think that means the issue is sorted, well, actually, this is where things go haywire. I quickly found that some of my old standby's had new surprises when smoked in pipes well outside of the standard 19mm VA pipe. HotW, a blend that I considered a dull confectionary dripping in caramel when smoked in a standard pipe became transcendent when smoked in a 22mm bowl. Union Square particularly seems like it was designed to be smoked in a wider bowl, which may in fact be the case.
So, what's a guy with a normal budget and a taste for VA flakes to do? Buy a pipe that smokes well and never mind the bullocks. Really, you'll learn to appreciate whatever you're smoking with whatever pipe you have on hand. Varying the width just tweaks the flavor profile. FVF won't become Capstan. These aren't massive changes and frankly, if you aren't paying attention you may not even notice. Maybe.
I know Jiminks likes to smoke FVF in a Sav 320. These generally come in around 21-24mm. I know I'm not the only guy around that goes well beyond 19mm with a classic VA.
A bit about depth. My preferred method of packing the pipe is with the airpocket (aka cannonball) method which leaves an airgap below the tobacco. As a result, the depth has minimal impact in the flavor of what I smoke. I know some folks suggest flavors become richer as the tobacco "stoves" in a deep, narrow bowl. I don't share that opinion and prefer the clarity of flavor provided by an airpocket.
When looking for a new pipe now I generally look to something 18-22mm wide and about 30mm deep. My first consideration these days is weight as I know diameter is nothing to worry about.
Edit: Imo the difference in smoke temperature between a nose warmer and a long canadian is imperceptible in briar pipes. The only time I've experienced variance in smoke temps is when smoking a block meer pipe, which imo smokes perceptible cooler that any other material regardless of length.
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