Ombow, >> 20 or 30 years down the road <<
They don't take that long, usually 1-2 years for the stock to get its mojo back, and meanwhile you get a good dividend. Things could still go wrong, but the odds are stacked in one's favor since these are historically solid stocks, temporarily out of favor (hopefully).
It's also possible to get big rapid gains with beaten down contrarian value plays - sometimes you could get a fast double within a couple months (TEVA). But that's not easy since you don't know where the exact bottom is.
Momentum investing definitely has its advantages - the main one being that the stock is already in an uptrend. According to the general 'rules' of trading, the best odds of success are to only buy a stock when it's in an uptrend. In momentum trading you are always buying during an uptrend, so in that regard you are putting a lot in your favor.
But momentum stocks are usually the market darlings, the flavor of the month stocks, expensive and priced for perfection. And momentum traders are gunslingers, quick to exit at the first sign of trouble. You'll need to head for the exits ahead of a trigger happy crowd.
I can't speak from personal experience, but using chart/TA signals would be especially helpful with momentum stocks. Obviously if the uptrend goes parabolic, that's a danger signal, or if the RSI goes to 80-90 would be a red flag. Or if bearish chart patterns develop to suggest the end of the uptrend (head + shoulders), combined with volume signals. The momentum gunslingers will be using every TA/chart signal in the book.
