Doing exactly that in my account 400,000 DEC in the account and 269 SPS after 5 days. However, I'm still losing at this moment.
Remember, DEC goes up and down so no guarantees you'll hold your initial investment there. Also remember SPS goes up and down so no guarantee once all 3 billion are printed. Also fees to bring in money from outside HIVE and when you buy the DEC.
Plus when Vouchers are done who knows what will happen to SPS price. Then when people are buying cards on market after Chaos again what happens to DEC price?
Love your idea but there are a few risks involved and I'll be watching them carefully on my blog over the next year :)