They all have openings on top that become clogged quickly with falling debris. They can collapse from the weight of snow, ice and birds. It's more difficult to pick the debris out of them then it is out of the gutter. You can lose sections due to powerfull wind gusts. They are typically low in cost and low in performance. Limited or no warranties

They tend to collapse at the bending points, due to the weight of snow and ice. A lot of expansion and contraction during the months of winter and summer, can lead to shifting of the panels away from their clip systems and into the gutter. Warp and discoloration may happen due to the heat. Critters can and have chewed through vinyl products. Generally speaking very weak warranties. Can't handle the rain water flow like Gutter Cap. Often times the vinyl endcaps, will not come with them to keep out unwanted animals. Cheap to install and cheap on performance.

Brackets can restrict the range of application in regard to the roof pitches. Some systems use a bracket every 5', which can lead to a weakness in the middle of the panel. Manufactures tend to change the brackets style and type due to the problems related to previous brackets. Some examples: rust spots, warping. If roof needs to be re-done certain bracket in-stalled systems will never go back on the same. Difficult to remove vs. Backing out screws and re-installing of gutter cap. The more componets that go into a system the more chance of installtion error. Many claim their strong by supporting the cover with all those brackets. However, most homeowners will not be standing on their gutters. What they should focus on is performance warranties. Also if you have inconsistent placement of the nose due to inconsistency of the existing gutter. (placement of the nose of a product should be flush with the outside of the gutter lip, not forward or held back passed the inside lip.)

A homeowner has to replace their gutters even if they're in good shape. If any section is damaged due to hail, roofers, or homeowner related, the whole cover or cover and gutter must be replaced vs. Just a 5'section. One piece systems do not use soffit and fascia. Where's the protection for the exsisting wood? Some one piece systems use 3" gutters. The capacity of water flow is cut in half.