Now that ASICs are truly out into the wild, roughly what increase percentage could we expect per month in difficulty? I am considering an ASIC order but I don't want it to be a paperweight on arrival...
I'm in the same boat. Just about to pull the trigger on a Bitfury setup with 4 cards (100GH/s=$2800). So, this is my thought process:
1 April it was 6.6M
1 May it was 10M (+3.4)
1 June it was 12.1M (+2.1)
1 July it was 21.3M (+9.2)
1 August it was 31.2M (+9.9)
The last month has had an average of 9.5M increase.
Today is the 9th of August, not yet the middle of the month, and difficulty is 37.3 (+6.1)
So if this continues, we'll probably see an increase of 15-18M from 1 August to 1 Sept, leaving the difficulty at 46.2 to 49.2
If I was a betting man, due to the amount of ASIC's hitting the market in September through the rest of the year, i'd bet it's safe to probably double that number (i'll go with 15, so than means 30M) for every month after September. So, assuming 1BTC=USD $100:
1 September: 61M to 1 October: 91M. Average is 76M. @ 100GH/s with $0.30 power (100W)= $1951 after power costs. ($22)
1 October: 91M to 1 November: 121M. Average is 106M. @ 100GH/s with $0.30 power (100W)= $1392 after power costs.
1 November 121M to 1 December 151M. Average is 136M. @ 100GH/s with $0.30 power (100W)= $1080 after power costs.
1 December 151M to 1 January 181M. Average is 166M. @ 100GH/s with $0.30 power (100W)= $881 after power costs.
1 January 181M to 1 February 211M. Average is 196M. @ 100GH/s with $0.30 power (100W)= $743 after power costs.
1 February 211M to 1 March 241M. Average is 226M. @ 100GH/s with $0.30 power (100W)= $641 after power costs.
So, I think realistically... If you spent $2800 for 100GH/s, recieved it 1 November and hashed until the end of the March 2014, you'd have ROI and a $545 profit.
Now i'm able to afford a new H-Card ($500=25GH/s) and have it installed and hashing at the end of March. So my realized gain since the beginning of November is $45.
At this point, I think the ASIC arms race will cause difficulty to plateau a bit, having chased all the GPU miners off and probably the guys who bought a single Jalapeno or have just a few Block eruptors. Only the people who have 50GH/s or more will stay in the game. so instead of the monthly 30M increases, let's call it 20M increases.
So now with 125GH/s and 20M increases per month:
1 March 241M to 1 April 261M. Average is 251M. @ 125GH/s with $0.30 power (125W)= $717 after power costs.
1 April 261M to 1 May 281M. Average is 271. @ 125GH/s with $0.30 power (125W)= $663 after power costs.
At this point, you've made $1380. Time to buy a few new H-cards, don't you think? Buy two H-Cards (50GH/s=$1K) Hashing power is now 175GH/s and power costs are $38. Your profit since you started mining is now $380.
1 May 281M to 1 Jun 301M. Average is 291M. @ 175GH/s with $.030 power (175W)= $863 after power costs
1 Jun 301M to 1 Jul 321M. Average is 311M. @ 175GH/s with $.030 power (175W)= $805 after power costs
1 Jul 321M to 1 Aug 341M. Average is 331M. @ 175GH/s with $.030 power (175W)= $753 after power costs.
Now it's August 2014 and your profit since you started mining is $2801
Okay, i'm not goig to keep going on, but you see the picture. You are going to have to keep buying hashing power to stay profitable above ROI. I know that difficulty will not be as linear as that, but it is my conservative guess on starting with a 100GH/s/$2800 investment. I'f i'm being too conservative, then i't just a faster ROI and more profit. But others are saying the difficulty will be as high as 500M by the end of 2013. Who knows? Time will tell. But I DO know you won't make anything if you don't at least try.