I did the same thing, I found Firecore took up too much memory and would cause Plex to crash with an out of memory warning. So when the 4.4.4 unteathered JB came out I used SSH also and it has worked like a charm since. It been going strong for over a week with no errors.

I do suggest that if you havent to make sure you turn off updates so if Apple sends out an update your ATV2 won't take it.

This is the guide I used Plex Through SSH

There is a section that outlines how to stop updates from happening and breaking your Jailbreak

If you did this already you should be good