Powering down is always a good idea.

Powering down liquefies 1/104th of your SP per week in to Steem. Guess what increases by lots more than 1/104 per week? You guessed it , SP. You can power down and you will have more SP the next week than you had the last. Powering down is like a thank you for holding SP. Lets say the price of Steem goes to $100 per coin. If I have never powered down my SP I might only be able to withdraw 5 SP per week. But if I already powered down for a few weeks I now have a good amount of liquid Steem. Lets say the price dips to 10 cents. If you have been powering down you can power up that Steem right back in to SP and then power down again until the price corrects. 9 SP are allocated for every 1 Steem. It's actually even more than that right now I think 27 SP per Steem right now are being created during the first year maybe someone will clarify in the comments. The point is don't worry so much about your relative slice of the pie. Just prepare to eat it later.