Would you survive without NX?

For sure yes, I remember when NX did not even exist, still trained up to around 6x or so with about 5%/hour at Dangerous Valley II, Red Drakes. Definitely could do without, though I will admit pre-BB sometimes it was annoying in some situations (Not being able to find a map that is good to train), so I would get NX and just 2x card through the night to get out of certain training spots. Now it is different though, since BB has changed much things around, 0 - 120 without any NX is fine.

121 - 200 is a bit of a different story though, but we will leave that for another topic.