It depends on the future difficulty. Estimate what the difficulty will be over the next 6 months and then compare the revenue and costs for both options. If you can't do this then you should stay away from mining because you are going to lose money.
Ok for those who have had the same question...
I worked out two estimates, both with revenue and costs and one with an average estimated increase in difficulty and the other with a much greater increase in difficulty. Based off of Cloud Hashing contracts (2 yrs) and calculator and the current bitcoin price.
On the average increase it was just a little over 10 wks to make your money back.
With the greater increase it was about 13/14 wks.
Anyone here with a 20/GH Cloud Hashing Contract to verify these times?