Well, I´m of course as before totally focused on the yield and with difficulty increasing fast, doing all I can to make the yield surpass the increase. This I do by constant reinvestments between vehicles and reinvestment straight into my core instrument (about half of the whole). So, I rely a lot on compound interest. And I´m always on the lookout for trading opportunities. You really have to be on your toes in this crazy and fast moving marketplace.
I've found you a lovely difficulty chart at Coindesk galdur, which illustrates the slowing in BTC difficulty increases and may help you in your future investments
http://www.coindesk.com/data/bitcoin-mining-difficulty-time/20 May 2014: 6.9 billion start
27 September 2014: 34.6 billion finish
Net increase over 4.3 months 5x or 500% higher
28 September 2014: 34.6 billion start
11 February 2015: 44.45 billion finish --Today---
Net increase 4.3 months 28.46%
The last measurement over the last 4.3 months looks much better for my Havelock AMhash1 investment, I did it for those who prefer rigid historical analysis versus future modelling of economic conditions analysis
PS: xhomerx10 and explorer have been added to my ignore list