What sort of depreciation models are you guys using for your miners? When I first started I came up with an exponential formula to depreciate each miner monthly by 10% each month from it's previous month NBV rounded up to the nearest $25. This would make each miner fully depreciated around 2 years which I figure is close to the working life of a miner. I was also trying to find a balance between difficulty and BTC price, but since I came up with that formula the BTC price has exploded so I'm thinking of possibly changing me deprecation model and interested in what other are doing.
Won't fly with the IRS, I'm 99.99% sure they count cryptocoin miners as "computer equipment" (which they are per most definitions) and require you to use THAT insanely long (even for REAL computers) depreciation timeframe.