I own a 2012 343RL that I took delivey on in June 2011.
No issues with the slide system other than the cables on the main slide was out of adjustment which was corrected with warranty.
I did however change the springs after a 5000 mile trip to Charlotte NC last year. The 343 with 3 slides and the kitchen on the left side is heavier by approx 800 lbs on that side.
When we got home I noticed the trailer was leaning to the left where I could see the springs were flattened on that side. I replaced them with heavier duty springs on both sides outside of warranty.