I agree with the notion of "Miners, sell higher!". If BTCs were worth their high of $8.90ish before the difficulty increase, they ought to be worth at least $8 plus the proportion of increased difficulty, so just shy of $11 each, in my estimation. However, let's not forget that the market is already overpriced (obviously, as prices have been flat-to-descending for a while). It's fundamentals are hard to ascertain, as it's somewhat like gold, but better, yet not as well known and not as well traded.
I made projections back in late April as to what I think the current BTC value would be now, based on the supply/demand fundamentals of difficulty increases and other predicted (even if only psychological) fundamentals. My original prediction for today's date was $3.23, vastly different from the $6.90 to $7 that we're seeing today. About a week later I revised that prediction (based on more information) upward to $4.76. Still a far cry from $7
Given that current prices are 47% higher than my last prediction, that'd put us at $8.62 by May 25th, $9.03 by May 31st and $11.55 by June 11th. As always, we'll see...