TLC was a serious downgrade from MLC, especially in smaller capacities in steady state. The thing that made TLC good is the 3D process, which greatly improved the robustness of the NAND. 3D TLC did not come out until some time after planar TLC drives were sold.Funny, the same thing was said about MLC when MLC came out, and then about TLC when TLC came out. And now we use both without issue, and we'll be using QLC without hesitation in a year too, because the reality is it has plenty of write cycles and people way overestimate how much they actually write to their drives.
QLC is a lot worse than TLC.
Judy: "It's safest to drive with both hands on the wheel in the proper positions."
Judy: "However, it's probably okay for you to drive with two hands somewhere on the wheel."
Jack: "I know, but I can drive all day long with just one."
Judy: "Okay, but you shouldn't get reckless."
Jack: "Hey, today I'm going to drive with no hands, just my knees."
Judy: "Not a great idea."
Jack: "Oh really? Tomorrow I'm going to try driving with nothing but my feet!"
Judy: "You have to be trained for that and maybe need a special car."
Jack: "Well, I plan to evolve from this to driving with just my mind."
Sometimes the slippery slope is real. There is a limit to how many voltage states NAND can effectively handle.
Anandtech just posted a review that shows the Intel 660p to be particularly terrible in multiple metrics. Latency is bad. Write performance is bad. Steady state performance looks troubling.