A little over a week ago, I wrote a blog post where I explain why I move my SP from my main account to a SP holding account.
Basically it introduces a new layer of security.
The SP holding account is generally inactive, isn't used for voting (other than witnesses), posting, playing games, doesn't automate any kind of behavior which requires private keys, doesn't authorize apps to do stuff with the account. In fact, it should not do anything except wallet operations and delegations. And once the transition process is over from the main account to the SP holding account, there should be mostly delegations, and very few wallet ops.
While you might say anything below the active private key is harmless and the worst a compromised account can do with such a key is get involved in spam or flag wars, it isn't necessarily so. Because at some point, by using the account more than necessary, you might use the active (or owner) private key by mistake in the wrong place. And that's all it takes.
That's why I prefer to keep the SP holding account inactive and separate it from my main account.
Plus, it adds 5 more days to a compromised account, before the SP becomes available to power down (since it is delegated).
Sure that thing works both ways. If you want your STEEM liquid to trade on the short term opportunities, this is not something you want to do.
But I already said some time ago that for me STEEM is for holding, I have other opportunities eyed for trading.
But why have I written this update? As a sort of a journal for me and whoever will be interested of what happened during this process.
I already mentioned in my first post what were my first steps then.
A few days ago my first power down cycle was completed and around 153 STEEM went straight to my SP holding account.
Today I decided to take one more step. I thought with the liquid STEEM I had on my main account, I'll have enough to match my delegation to 
Unfortunately I didn't take into account the delegation I had from 
Anyway, I went through and delegated to actifit from 
I also talked to 
Funny thing is, that this is supposed to be a move of the SP from my main account to my SP holding account and from there to delegate back to my main account.
So far I haven't delegated back anything! I started by delegating to the projects I delegate to from my main account, so I can undelegate that SP from my main account.