The other manufacturers just don't seem to be inclined to spend the extra time and money to deal with flaws, other than those that hurt short term sales.
I get what you're saying, but in this case "the other manufacturer" is Micron.
Micron Technology, Inc. (NASDAQ: MU) is an American multinational corporation based in Boise, Idaho, USA, best known for producing many forms of semiconductor devices. This includes DRAM, SDRAM, flash memory, SSD and CMOS image sensing chips. Consumers may be more familiar with its new consumer brand Crucial Technology and retail subsidiary Lexar Media. Micron Technology is among the worldwide top 20 semiconductor sales leaders. Micron and Intel together created IM Flash Technologies, which produces NAND flash memory.http://en.wikipedia.org/wiki/Micron_Technology
I own both a Crucial M4 (Marvel) and a OCZ Agility 2 (Sandforce), and fortunately have had zero problems with either of them.
In any case, the OP wanted opinions on Intel's 520 (Sandforce SF-2281 with Intel's firmware) and Crucial's M4. Both of these designs are trustworthy, in my opinion. The M4 has a proven track record, and the 520 benefits from Intel's firmware.