It is very shady but a lower BTC price would mean higher maintenance costs in BTC terms so a lower payout would have to be expected.
In order for maintenance costs to not be considered a "hidden fee", they would have to be stated, which they are not. By claiming they have "No hidden fees", they're saying the fees are included in the upfront cost or the fees are well stated. They're neither in this case.
These question are not specifically for you, they're for anyone to answer. The quotes are just for context.
All is adding up... Even company from your sig behave similiar...
AMHash doesn't claim to have no hidden fees and their maintenance costs are explicitly stated. AMHash's dividend reduced by about 30 Satoshis at most, your dividends from here reduce by a couple of hundred. Given your payout from last week was around 835 Satoshis per Gh per day (which was slightly higher than AMHash's for that period), their maintenance costs would have to be similar to AMHash's. If AMHash only dropped by 30 Satoshis, how do you explain the drop in your payout of 269 Satoshis?
Their behaviour is in no way similar.
By 'No Hidden Fee' I understand at 0.001 BTC you get exactly 1 Ghs and there is no hidden cost to inflate the price. That is what they are doing. I could not find anywhere in the site, which talks about zero maintenance fee. Rather note in their mining calculator clearly indicates that there are some fees before actual payment. So, I am not buying your arguement that no hidden fee has anything to do with zero maintenance fee, which you are trying to force on them for some unknown reason.