i am a autobody tech. i have been using the HF 56" bottom box for the last 5 years it works OK. the slides have worn out on the top drawer, just replaced them with new parts from HF.
the standard HF boxes have OK slides. if you have a lot of heavy stuff in the drawers it will mess up the slides. this is the case with any other aftermarket box. when looking at the box you plan on buying i would suggest opening a drawer fully and leaning on it to see how they bend and support the weight before buying. most non name boxes are built pretty weak compared to the tool truck brands.

with that said i highly recommend looking at the new ICON line of tool boxes at HF. they compare directly with the name brand tool boxes sold like snap on and rest of the tool truck brands. the side lockers on these boxes look really nice. if i wasn't in the process of doing a custom modification car project i would buy the 72" box with side locker tomorrow and have no regrets.
in the store i have opened the bottom drawer and can stand in it without it bending, i am pushing 260lbs.
there is currently a coupon on the internet for 20% off your entire purchase of icon products. also i see a sign on the tool boxes they will give you 10% off if you finance it thru HF. i don't know if you can combine the 2 discounts, but my gut feeling is yes they will combine the 2.
i also see a FREE DELIVERY of ICON tool box purchases in the store display also.