There is no miner with less than 1W/GHS. With makes in 5 years 50.000 kWh witch is min 5$ power expenses. You are now saying that you for the remaining 3,75$ you want to change hardware several times? Beside costs of Hosting maintenance etc...
I beg to differ that there is nothing less than 1W / Ghs. I suggest you do a little research.
And even if you were right (which you're not), over 5 years there will be plenty of times to get more efficient power consumption as ASIC technology advances. It only takes 1 change to completely destroy your estimate of $4 over 5 years. Just ask the miners who are going to be changing out their avalons for neptunes, etc. Nobody will be mining with the same hardware 5 years from now.. that's just silly. That would be like someone still CPU mining for Bitcoins.Anyways, I'm going to go and compile my payout list (its payday today!
) so have a great day. 
Do you Change to new Hardware on you own cost? or do you customers who bought a 5 year contract today have to pay for this?
Research? You are note willing to share with us what kind of magic Hardware you are using ?
Changing to new hardware once over 5 years is a benefit for everyone, not a cost.. so of course my customers would not pay for it.
As for hardware, we are CPU mining of course.
(that's a joke by the way). If you can't trust a contract from a registered business with an established ebay account, and hundreds of satisfied customers then this game isn't for you.If you are willing to place a bet that we won't be around 5 years from now and still respecting our contracts, I would gladly bet against you. Would you be willing to place this bet?