I'm going to say that for the most part all computer devices of a particular model are going to function virtually exactly the same if the same Software is installed in them. They are all benchmarked as part of a final gamut of tests before leaving the factory and any that don't perform to within tolerances are pulled from production before packaging and shipping. Since these are digital devices, again they should all perform virtually identically through their entire life until some form of catastrophic failure occurs or if there is a corruption of data or firmware/software.
Generally the only other time when a device may perform abnormally is it hasn't failed is if the is a great related issue and as one or more components heats beyond tolerances the out of range resistances, capacitances and voltages cause logic errors that then become extra work for the error detection and correction processes and this results in a noticeable lag or freezing.
Unless there is some inherent PROBLEM such as just mentioned for example. Any device, whether new or older should perform virtually the same ONCE they are factory reset and the OS is refreshed from ROM.
In the case of the 4G failures that's a different game altogether since now we're talking about RF radio transmission and reception, as well as signal generation, modulation, amplification and filtering. Logic is pretty much a massive binary matrix of switches and gates, and they're all based on being in one of two states...off or on. If any one logic gate or switch fails there will be a logic error and then it's the error correction that addresses the problem.
