Buying bitcoin will have a lower yield and theres more 'work' involved following the market, but it has a better lifespan than hardware.

Shipping issues aside, if a unit like the Neptune doesnt fulfill its Q1 'promise' it should still arrive ahead of any comparable miner. Being in line for the first of a next gen product will give you an edge over other miners, but it could last between a month and 6 months.

In terms of your estimates in the first post, I would be using a far lower value for conversion, like $250/BTC.

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