Maybe put a link to whatever one you're looking at?
I bought two X2 Ku LNBs when I first got into FTA in 2013 and they both died within a year or so. I've been using a bunch of Avenger PLLs and a couple of generic LNBs I've picked up used here and there and haven't had any problems except for one Avenger that didn't work right as soon as it came out of the box, but the Amazon vendor I bought it from replaced it at no charge.
The X2's I bought were only like $5 and is the reason why I'd bought them, at the time I wasn't sure if I could get FTA to work and I didn't want to spend a lot on something I was unsure of.
Judging from the poor quality of the two I had, especially in contrast to how well the Avengers have held up and worked for me, I would say the X2 LNBs aren't worth buying, even at a low price of a couple of dollars.