I used Atom for 3 months over New Year's on a 4 GB 2015 MBA.
I had no issues whatsoever.
Interestingly enough, Atom seems to really struggle on my Windows laptop, it's often incredibly choppy. It actually runs better in a Linux VM than natively on Windows.
The only consistent issue that I have had with Atom since I started using it in late 2014 was the handling of large files. It has gotten incrementally better, as others have stated, but trying to open up, for instance, a JSON file larger than 10-20 megabytes in the editor causes the editor to be brought to a grinding halt.
I had no issues whatsoever.
Interestingly enough, Atom seems to really struggle on my Windows laptop, it's often incredibly choppy. It actually runs better in a Linux VM than natively on Windows.