Slotted Standard Based Modular Shelving?

Darkcobra

Hello! I hope this is an appropriate forum to ask this question.

I'm planning to put up a lot of shelving in the near future. For some of it, I've been looking into slotted standard based modular shelving, as the ability to easily add/remove/adjust shelves would be very handy for my intended purpose.

I told a friend about this. She said she used to rent an apartment that came with bookshelves built with these. Upon filling them with books, the metal tabs on the brackets that fit into the slots slowly bent, causing the shelves to progressively tilt, until books were falling off.

She also said she's worked in several retail stores which used these, and you had to be very careful how much load you placed on them, else the same thing would happen.

I thought perhaps she'd only encountered cheaply made shelving, and I pointed out the load rating on one of the systems I was considering, which was "up to 450 lbs./pair" of brackets. She then challenged me to find a picture of any shelving system of this type holding a respectably sized tube TV, or similarly heavy item. And I found I could not. Even the manufacturers' sample pictures for their heavy duty systems shows them lightly loaded, far below their stated load limits.

This is worrying, so I'd like to get a second opinion from someone experienced with these systems.

If I get something like Knape & Vogt's 82/182 series, which is their heavy duty system with dual slots and "up to 450 lbs./pair" rating, and follow all recommended installation procedures, can I expect it to hold 150 lbs./pair without the bracket allowing the shelves to tilt over time? Would dual slot systems from Elfa or ClosetMaid work as well, or are some brands better than others?