As far as X1E goes, BIOS issues have been resolved, so no problems there anymore.
As far as thermals go, they are way better then in MBP or Dell XPS for example. I have no problems with thermals or throttling at all.
But noise... Well, you will probably get some noise. But for that problem you will have to tweak a little bit. Undervolting + thinkfan utility will take about 2-3 minutes to setup, and that will resolve fan noise issue as well.
I would also suggest repasting, since a lot of laptops these days come with a really bad paste job to begin with. Mine did as well. So i fixed it myself. It's just a matter of few screws to remove the fans, apply the paste and put fans back in. Really not hard to do at all.
But most of the x1e owners here didn't do that at all, and they have no fan issues. In 99% of the cases simple undervolt+thinkfan will be enough.
It was even for me, but I went an extra mile just to keep my mind a ease
Since 2012 and rMBP, I haven't had a better laptop. Build quality is excellent, x1e is a tank. Keyboard is way better then any other keyboard out there, and port selection is awesome.
Only thing lacking is battery life (I get around 6-7 hours with FHD screen), but battery life isn't my biggest concern. If you need more then that, well, then X1E simply isn't for you.
Other then battery life, I can't find any negative about this device. It's awesome in every aspect.