How good it could have looked if only - external link; http://slamthatstem.com/image/44792341670

I think it looks better with the taller ht and tt slope.

For me, the problem with it is the straightness of the back of the HT. If they had a UCI-illegal version that had that curving into the TT and DT, it would look much better to me. Dropping the HT only improves it in my eyes because it shrinks the length of that straight piece. This is also why it looks worse in larger sizes.

Low front end looks way better to me. I've just built a 58cm Cervelo R5 VWD for my brother. I just can't see why Cervelo insists on using such long headtubes these days. For a sportif bike like the old Cervelo RS, then it's underestandable, but not on their 'race' bikes.

Shorter headtube definitely looks way hotter.

And if they made the top tube dead level it would be even better, and more aero (think javelin flying through the air). And after all, isn't aero what Cervelo is all about. I think for every person that thinks their head tubes are too long now, there's probably 10 (myself inclued) that thought they were too short before they changed them. Still think the current headtube area is ugly, to agree with Toby's post above. And for those that do want to get lower, the -17 stems are a good option, but the -17 stems with the upward sloping top tube just becomes doubly ugly imo. You can please some of the people some of the time...

I do like what the OP did with the flipping back and forth graphical imagery. Makes it easy to compare.

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My Colnago C59
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Actually, level toptube is not any more aero in particular than sloping when proper airfoil geometry is used. They have different tradeoffs in the flow going between the legs of the rider

Yeah, but it would sure be nice to have the option of a shorter headtube.
Great graphic, by-the-by...

Is "proper airfoil geometry" being employed in that top tube? Forget the moving legs for a moment cuz that just destroys all aero stuff happening there anyway. I keep thinking of an arrow shot through the air. If it flys straight into the direction it is shot it is much more "aero" than if it somehow could move along in a vertical plane. Don't ya think. And you're not seeing too many TT superbikes without a pretty level top tube these days.

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My Colnago C59
My Special Colnago EPQ

I've never seen an arrow with a headtube attached in front of it.

It makes no difference. Specialized, Cervelo and many others have found this to be the case.

Yes, Cervelo has specifically designed the shape of the toptube. Have you ever read the S5 white paper? If not, I highly encourage you to do so

The Cervelo S5 "whitepaper"? Yes, i've seen it. I've read it. Cervelo's marketing boys were busy on that one. And there isn't one word about a sloped top tube being more aero than a level top tube... I skimmed it again and didn't find anything. I don't believe they mention the sloping top tube even once. They talk about their dropped downtube alot, but as far as the their top tube goes... not so much.
The reason you haven't seen a headtube attached to the front of an arrow is because 1) it's not necessary, unlike a bicycle, and 2) it would be plain stupid to wreck the simple and understandable aerodynamics of the "straight as an arrow" cliche. But if someone did want to attach a headtube to the front of an arrow, the arrow would still be at its aerodynamic best if it was flying straight as opposed to sloping, despite having a big ugly head tube attached to it.
Anyway, just my random observations. Like you say, it makes no difference really. I'm not slamming Cervelo, well, I guess I kinda am, but for what it's worth I do own a P3. Doesn't mean I buy into their marketing spiels.

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My Colnago C59
My Special Colnago EPQ

All of Cervelo's tri/tt bikes have pure horizontal top tubes. If sloping top tubes were faster, the tri bikes would also have it.
Pretty much all of the heavily researched, tested, studied pure aero bikes (which are tri and tt bikes) have horizontal top tubes and stems that are inline with the top tube. The Giant tt bike that eventually became the trinity advanced was designed by an engineering and aerodynamics firm with no ties to the bicycle industry, horizontal top tube, inline stem. Shiv. SliceRS. This is not coincidence, this is not conspiracy. It's convergence.

While I agree that the S5 would be much better looking if the head tube were shorter, it would affect aerodynamics of the bike negatively for MOST riders.

Most riders put spacers under the stem. Spacers in the wind are less aero than the shaped head tube. So it is actually more aero for the majority of riders to have the tall head tube and no/fewer spacers. I have heard from some reliable folks that this holds true for the P2/P3 as well - most riders would be faster with a P2 and the taller head tube with no spacers (of course, vanity often wins and they pick the "nicer" bike and slap a bunch of spacers on it).

It's sad for you and me, but really does make sense.

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Team Mike's Bikes

Those people with spacers are far more "unaero" and the bike under them doesn't matter anyway;-)

Give people in a more aerodynamic position the best option. Me, I would need a size 54 with a -17 stem slammed to get the right fit. At least the headtube on a 54 doesn't look too bad.

Who am I kidding, I'm not buying a Cervelo anytime soon unless I fall into some money. My money is reserved elsewhere.

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www.ergottwheels.com

While I would also prefer a shorter HT on the S5, because they went with the long HT, using a level top tube would add 2-3cm to the standover compared with a similarly sized, level top tube frame. While standover is way, way down on the list of important criteria in a road bike, there are people who might not buy it due to a lack of clearance. Think of shorter people with longer torsos.