If it is fully disclosed and you know what you are buying and are good with it then yes, they are safe. At least as safe as any other ES cpu is ever 'safe'. The remarking is a form of counterfeiting but if you know you are not buying genuine goods then so be it.
The real risk with remarked CPUs is when a unknowing buyer thinks they are getting a retail CPU and are really getting one that is a 'similar' ES device. This is fraud.
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