Truth of the matter is, this change in the algorithm is really not good for small miners. I used to get 10-15 Diamonds per day. I spent two days trying to figure out how to mine groestl, dealt with all the issues we all have, and I've gotten 2 Diamonds since the change. I don't think I can solo mine at the current difficulty - I only have 3 decent graphics cards, probably 16-20 Mh/s total if I use them all for Diamond. And there are no pools that work. Lower fan noise and lower energy consumption sound great, but I'm just not making any profit. Diamond mining is off the agenda for me until something changes.
that have nothing to do with changed algo
its more people want to mine so diff is higher
mining diff is same as exchange price a indicator of coin value
and same as some people stop to buy at at price xy some people stop mining at difficulty xy
some others seem to belive diff is still low enought to make this worth their mining time
special combined with a calculation of power cost