I broke a Sram X7 shifter, 35 quid to replace. Times are hard so I bought the x4 for 19 quid. The young dude in the shop urged me not to downgrade; "the X4 will be nowhere near as good as the X7, I'm not pulling your leg, I'd strongly recommend that you get the X7". With a heavy heart I stuck to my guns and went for the cheap x4.
Went out on my favourite blacka moor route today - x4 performance exactly the same as the x7. weight the same. The only difference between the two is a few more plastic parts rather than alloy.
Lesson: DON'T BELIVE THE HYPE.