As you know, @spinvest was criticized by some curators as being a sort of egoistic reward tool that does not add value to Steem. This is of course not true. But by advertising a SP power down you nourish these allegations. I mean it is one thing to power down, but to even advertise it?
I am also in SPI but I would not put all money in it. There is a risk of a "bank run". If for whatever reason all want to sell their SPIs at the same time, it could become ugly.