What is ROI standfor? Return On Investments?
Yes.
I think it may be premature to say that you would NEVER ROI with current mining rigs.. I think the question is
what is an acceptable time frame for your ROI, and this is subjective.
A few years ago I was mining on several different computers on Slush's pool. At the time my mining was not profitable, as I was spending much -much- more on electricity than I was getting in BTC. I mined about 8 BTC, which was worth about $40, and it cost me at least $100 in power alone. Now, had I held onto those coins, I would have seen a substantial ROI -a few years later.
So really it depends if you see long term use and adoption of Bitcoin to justify the risk of making the investment in the gear.