Have procured two separate limesdr-USBs and both fail LimeQuickTest, looking for advice

The test is only valid for a cold board,

Part of the test result, that you omitted shows the temperature e.g. “Chip temperature: 27 C”. So if your board had been powered on for more than lets say a minute there is the potential that the elevated temperature (especially during summertime) could be the cause. That it is only 0.7dB above a pass would make me think that temperature is probably the cause.

Provided there is cooling I do not think that there would be any issue with continuous operation on the 23 or 70 centimeter amateur bands (with external filtering, if it is being used for TX).