During the few weeks I spent researching SSD's before I bought my 256 GB Crucial C300, I found that the speed of the drive increased with the size with all manufacturers. At first I was only going to buy a 120-128 GB drive but when I saw how much faster the 240-256 GB drives were in real world use I couldn't resist going with a 256 GB model.

It's been a while since I read into it, but it has something to do with the way the actual chips are made. There's an actual physical limititation keeping 64 GB drives from being anywhere close to as fast as their 256 GB older brothers.

I thought this was common knowledge among semi-educated SSD consumers?

funny....but good [for me].i have a Sammy in my (not too) low end 13".....and Its flying too!

I suppose there might be differences since one company may be trying to get around their competitor's patents and still offer a similar product.

Ignorance of SSD Technology causes bad articles to be written.

I too have a entry level 2011 13" Macbook Air and have the Samsung SSD. I was getting about 265MB of read when I ran DiskSpeedTest

I couldn't bear reading people's attempt to explain the speed differences without necessary SSD knowledge. I had to create an account just to post my 2 cents on the topic.

This is what I know about SSDs:
1) Larger capacity SSDs typically have shown faster read/write speeds. This is because larger SSDs use larger GB per chip in its constructions. This gap used to be something like 20-50% difference per storage size level (64GB vs 128GB vs 256GB). Anything larger than 256GB used to double stack smaller RAM chipsets to achieve size, but have similar performance as the 128GB or 256GB counterparts. Newer generation SSDs have shown a smaller performance gap between capacity sizes.
2) SSD speed is greatly influenced by the SSD controller and chipset construction. Samsung has 22nm chips and are more efficient and faster than the industry's normal 32nm construction --Toshiba?). However, SSD chipset controllers can make a significant difference for the same chipset construction---a difference large enough to explain 280MB/s vs. 180MB/s (see OCZ's Vertex 2's 280MB/s vs. Vertex 3's 550MB/s using the SanForce SF2200!). Variation in performance among manufacturers are evident in the SSD world.
3) Use ATTO or HD Tune Pro (both are Windows programs, but it's the standard benchmark tools for PCs to test SSD speeds) to see if the speed difference is a random issue or a fundamental one.
4) I own a Vertex 3 SSD, had had SSDs with 60MB/s, 150MB/s, 180MB/s, 285MB/s, 550MB/s and 700MB/s (Revodrive x2) experience and the OS experience is marginal after 200MB/s speeds. The sweet spot for the industry for price to speed right now is the 128GB doing mid to upper 2XXMB/s. Anything above this is like buying a Ferrari instead of a normal sports car (BMW M3, let's say).

I would not be happy to know that the speed difference is a 50% difference. I would be interested to see how fast the difference is between the 64GB and 128GB SSDs on the MBA 11" MBA as well as the 128GB vs. 256GB on the MBA 13".