Currently running on Fedora 20. I have been using a OCZ Vertex 4 for 1.5 years, on EXT4 with TRIM enabled (discard option) plus using fstrim on the same file-system.
I have been doing that since at least Fedora 18, never had any problems with discard on EXT4 (this should be the default file-system on Ubuntu 14.04).
Now, EXT4 and TRIM are only linux-kernel code, and I doubt there is any difference between Fedora and Ubuntu. Since I've been using Fedora, that changes kernel versions like they are shirts, I can guarantee you that discard works just fine, and has been working fine for a few years.
The issue probably is that some SSDs have buggy firmware that cannot handle large queue depths of TRIM and read/write requests.
Anyway, I would probably enable discard and test it, after having backed up everything of course.