I was in the same dilemma. I went from a Aluminum Macbook 13 Unibody 2.4 to a 1.6 Macbook Air Rev A. It had the stuttering video problem so I went with a 1.86 Rev C. It was much cooler temp wise than the 1.6, battery life was almost the same, and most videos played better on the 1.86 than on the 1.6 Rev A.
But one day I was trying to watch the HD video on the Apple website about the Hubble. Its under trailers.
On the 1.86 Macbook Air it was dropping frames like crazy!
I picked up the 2.4 Macbook and it played it perfectly.
The next day I went to Bestbuy to do a test.
I put the same video on the Macbook 2.26 Unibody 13 and then on the Macbook Air 1.86 they had on display.
Exact same results. The Macbook Pro 13 was smooth as butter. The Macbook Air was stuttering. And I noticed a few other things as well.
The Macbook Air screen can get brighter than the 13. But.. the colors on the Pro 13 were richer. And it was a pretty easy to see. Also the strange thing about the screen on the air is that straight on the whites were white. But when you went to the left or right the whites started to look yellow.
This did not happen to the Pro.
And last but not least when going to a website or opening apps..the Pro machine was noticeably faster.
I was a big fan of the Air for a while but if you can handle the extra weight the Pro is the way to go. Once they update the Macbook line..I'll get the new Pro. Or maybe the new Air if its improved upon. But for now...my lust for the Air is gone. Well....maybe just lying dormant!
Your update from a 1.6 GHz to a 1.86 GHz wasn't the difference in your performance. That came from it being a Penryn CPU operating at 17W versus the 20W Merom CPU in your original MBA... AND, the Nvidia GPU in your newer MBA being far superior than the original MBA's Intel 3100.
I wouldn't recommend anyone buy a "rev C" 1.86/HDD new because they can get a much faster and more capable MBA by buying a "rev B" refurbished and save $150. For $150 less, everything is the same except you don't get an ethernet/USB cable, but you do get an SSD that will reduce the bottleneck and give the MBA an incredible improvement over the newer 120 GB HDD. It's too bad not enough people realize the differences before buying.
From what you've reported here, it doesn't seem you have ever used an MBA with an SSD. The SSD changes the performance of the MBA completely. It makes an MBA feel faster for most normal tasks than a standard MBP with 2.53 GHz CPU and 7200 rpm HDD.
Remember the bottleneck for most computing tasks lies in the bandwidth/transfer speed of the drive. An SSD can access files over 10X faster than an HDD. The stock SSD reads upwards of 8X faster and writes 1.5X faster than a stock HDD. It makes a huge difference to the end user for normal computing tasks. Add in the RAM limitation and the much faster process of swapping with an SSD. I don't believe anyone has ever truly experienced an MBA and its full/true capabilities if they haven't used an SSD for a few days to realize the change in complete system performance.
To further the SSD phenomenon, a Runcore SSD will operate 3X the speed of a stock SSD. One truly hasn't understood the capabilities of the MBA until they have used a Runcore SSD in a capable MBA (meaning any Nvidia MBA) for a few days. Put any Nvidia MBA to a test and be prepared to be stunned!
The MBA does have some graphics limitations, but most of the problems I have seen when playing HD content is when running a video through a browser plugin. I haven't had any problems downloading HD content and playing it directly from a video player. However, when running an HD video via Hulu or YouTube can lead to problems within the browser. Even in a MacBook or MacBook Pro, Flash and HD tasks can hit the CPU very hard within a browser. Add to that the 9400m in the MBA is underclocked due to its limited space for cooling... and that's the only performance difference between the MB or 13" MBP and the MBA.
I am surely not saying the MBA is as capable as an MBP... it's not. But the MBP isn't that far ahead of the MBA. I wouldn't choose an MBP because for me the weight is not worth it as I don't need the ports, I wouldn't use the optical drive, and I can live with not watching 1080p inside a browser.
At the same time, I surely hope the next MBA update narrows the gap further in video playback performance differences. The MBA is really quite capable, but imagine it with a Core i7-640LM and an Nvidia graphics system using Optimus for hybrid graphics support between an Nvidia 3XX and Arrandale's IGP. WOW, we're talking Sony Z type performance!