We had our contractor install these slides in our 20 year-old cabinets and we are very satisfied with the result. The drawers now extend all the way out and have the soft-close feature found on newer cabinets. Definitely worth the cost.
I used a pair of these for a trash/recycle cabinet that I built, with a pull out drawer. Heavy duty rating seemed more than enough for what I was using them for.
I do paper crafts and needed a drawer to hold my 12x12 paper booklets that are incredibly heavy. My husband built it using these and it is fantastic. No more back strain lifting the paper.