[H]ard|OCP just wrapped up a review of the 120GB Samsung 840, using their own ARM Cortex R4 based MDX controller and TLC memory for storage.  They compare the speed of this drive to the 256GB 840 Pro, Kingston's V300 120GB and the Intel 335 240GB to contrast the difference the type of NAND used can make to performance.  This is especially evident on the write and latency benchmarks, which fall well behind the competition.  From [H]'s testing it is apparent that TLC memory is very vulnerable to reduction in size, the reduced channels really hurt performance and put the 120GB model far behind the larger sized 840s which they have tested with much better results.

"The 120GB Samsung 840 Series SSD features the powerful 8-channel MDX controller and TLC NAND. While this value SSD comes at a very good price, it also features much lower speeds than its larger capacity brethren. We put this value SSD through our suite of steady state tests to see if it can pass muster."

Here are some more Storage reviews from around the web:

Storage