You may be facing compatibility issues when deploying certain switching features that aren't supported on those consumer switches.
For instance, you have to deploy a VoIP design with extensive QoS - you won't get the needed features from those switches.
Other designs can also present a challenge.
If you consider that computer lab a pure test network, then I don't see a problem using a consumer switch to extend network connectivity and it shouldn't harm the upper layer switches but they will offer quite limited services.
HTH,
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Edison.