Now, 700 grams is impressive and all. But I judge mass savings based on the marginal cost of attaining them.
Usually mass is confounded with functionality, but on the Cervelo R-series, with identical geometry and similar ride characteristics, I think it's safe to say the upgrade progression is mostly a weight weenie play. So I'll resist the temptation to compare it with the Guru Photon, a fully custom frame of comparable mass at half the price. Maybe the Cervelo is simply better. But comparing to the other Cervelos in the R-series, to which Thor Hoshovd himself claims the ride is similar:
It's all about marginal cost, though. That is trivially calculated:
R3 → R3SL: 64 grams @ $14.07/gram
R3SL → RCA: 103 grams @ $48.54/gram
To put $48.54/gram in perspective, a bottle of Odwalla juice costs around $3.50. But by this gauge, what's the real cost? Suppose I drink a bottle of Wholly Grain I don't need: 400 kcal. That will cause a weight gain of around 52 grams. At $48.54/gram, that's $2500. Wow -- that's a helluva cost multiplier! It's pricier than a typical price of my 860-gram Fuji SL/1 frame. Indeed you can get a SRAM Rival-equipped Scott Addict at Bike Connection in Palo Alto for less, pedals included.
So how will climbing improve, day in, day out? Here's a typical weight variation, measured with a high-end body mass scale (from the DC Rainmaker blog):
Day to day weight for this guy, a highly trained triathlete who carefully weighs himself the same time each morning, is up to around 800 grams. When riding, you sweat around 500 grams per hour on a hot day. Even if you drink from a water bottle to replenish this, the weight is coming off your bike or you, one way or another. In the time it takes to climb Old La Honda, therefore, you're probably dropping around 150 grams: more than the mass difference between the R3 and "Project California". Just think: in the time you climb Old La Honda on that hot summer day, you increase the value of your bike by $7300. That's $6.75 per second of sweating.
And before you tell me weight on the frame is so much more important than weight on the body, why do you carry your water bottles on your frame as opposed to on a belt? Q.E.D.
I love weight weenieism: no question about it! But my limit is around $4/gram. With that as a crude limit I've gotten my race bike down to just below 5 kg. $58/gram? Insane... There's so many cheaper ways to save that mass, off the bike, off your shoes, off your helmet, off your clothing, maybe even off your body. And watch out for those Odwallas.
But I still admit I think it's cool.