With Silk Road done and gone, we are looking at a long, slow death of Bitcoins, at least until another Silk Road pops up. I speculate that no one in his/her right mind should buy a miner or invest in BTC right now; the only logical thing is to sell, sell, sell NOW.
You really think people have been buying bitcoins because of Silk Road? People buy bitcoins because of its innovative potential and its future use, nobody cares about what it's currently used for. SR means nothing in the grand scheme of things, and alternatives are already springing up left and right and you can bet on it that the next Silk Road(s) will be even bigger because of all the publicity it got lately. So you go and sell right now please, while I am happy picking up the cheap coins.
Ontopic: Right now it's better to buy/trade bitcoins, investing in mining remains risky because of uncertainty about (timely) delivery, the bitcoin price volatility and the exponentially rising difficulty. Any of those three could completely screw up your ROI. If you just want to mine as a hobby that would be fine I guess, just don't expect to profit from it.