You are correct and I did take a shortcut with my words.
However, I don't think smaller = slower is always the case. The 80 and 160 GB Intels are roughly identical in speed, whilst the small Sandforce drives appear the equal of their beefier brethren in the specs stakes.
The cake is a lie. Oh and the sandforce specs lie too.
Manufacturer specs on maximum sequential write speeds compared to Actual test results for Sequential Write speeds:
Drive Spec Test
X25-M G2 160GB 100MB/s 101.2
X25-M G2 80GB 70MB/s 81.6
X25-V G2 40GB 35MB/s 37.7
C300 256GB 215MB/s 203.0
C300 128GB 140MB/s 131.1
C300 64GB 70MB/s 71.0
Corsair F120 275MB/s 136.6 or 214.8
Corsair F40 270MB/s 72.5 or 210.4
There is a clear progression from larger is faster to smaller is slower. Word on the web is that the 120GB Intel drive performs the same as the 160GB drive but other than that there is a measurable drop in speed from each capacity drop. On top of that Sandforce drives don't live up to the promised spec.Sandforce drives are clearly faster in some scenarios but on average they are slower than they advertise being. And that difference is more pronounced at lower capacities.
You might also note the Intel drives are the only one of the 3 that test better than their spec.