Also, as a bitcoin miner you should know, to calculate your profit you should count inputs and returns only in bitcoins - how much bitcoins did you put in to buy hashrate, how much bitcoins you got with mining. Because that last sentence always apply: why not buy btc instead.
Thanks for your thoughtful comments ujka. The amount I have been re-investing through the RRP has not allowed me to maintain a level production rate and keep up with the increasing difficulty, as per my first paragraph. Is it possible if I had re-invested a higher percentage, perhaps closer to 100%? I doubt it, but even then I've got to take some earnings along the way.
On looking at inputs and returns in BTC only, my contracts are way behind, and I would have benefited from more research in advance to verify their projections. On this basis I don't get how anyone can make mining profits right now. At CEX, the cost per GH/s last I looked was around 0.045 BTC, and based on their profit estimates (linked at bottom of their page) the expected output was 0.022 BTC (quoted as 2.2 BTC per 100 GH/s). Isn't that an expected 50% loss on BTC capital? I might be missing something, but its not stacking up for me.
Anyway, cheers.