Hey. Good question! Over the week I've been looking at this I'd say:

• Generally value has been pretty good. "Upvote / SBD bid" has averaged around 160% excluding Saturday (when the powered up service was new and returns were huge). Even removing the 25% curation that would be 120%. So a little value boost and free promotion for your post.
• Late morning / midday UTC windows (4th and 5th) have offered the best returns. These are the ones I'll be checking out in future.
• Value has been trending down over the week, probably as the service becomes more well known.
• Not too much evidence of late bids piling in to reduce the value of a window, except for the two low return windows on Friday. I would suggest always checking the steemd.com site (link in the post) before investing to see the likely return.

I plan to compare across booster, minnowbooster, and randowhale to see which offers the best returns, and when. Check back for this later!