Although there are several different mechanisms (electric, hydraulic, etc.), most RV slides are made by one or two companies - regardless of which brand of RV. For the most part, they are reliable. Of the thousands of posts I read on four different RV forums, VERY few of them involve failed slides. Of course, like all things mechanical and man-made, things will fail. Personal experience: three years full-timing with over 170 "round trip" actuations of two "full wall" slides and a bed slide and we have had no problems at all.
Rob