I think the key word is "trend", here.
Risers have a couple of characteristics that might be advantageous:
1. They're wider than most flat bars (which are generally max. 23" wide)
2. They've usually got more sweep that flat bars
3. They position your hands 0.75-1.5" higher (which can also be accomplished with a slightly longer and larger angle stem).
Regarding the above: wider bars offer more control downhill, but seem to make steering a bit twitchy going up steep ascents. Wider bars are helpful when mashing while standing, but the tradeoff there is they stick out (into trees) more, too. They can alleviate back problems, but also create them (I suffer quite a bit if I sit too upright!).
In the end it's all a question of what works for you. I prefer risers, but since I killed a bone in my hand I can't hold a single hand position for too long, so I'm back on flats and barends for a while. I may just like it, too. So I say get a cheap riser, or borrow one, and experiment. If you feel more comfortable or more agile with a riser, that's probably the way to go for you.