I have an 07 C50 with the 1 1/4" Cobra bars on. No problems at all. If you haven't installed them yet, make sure you have all the bolts started before tightening. I momentarily had pegs on mine but couldn't get them positioned to where they fit comfortably, so I took them off.
with the bars you will lose some turn angle. depending on what you bought. cobras have alot of curve to them and can reduce how aggressive you take a curve/turn. Take riding w/ them at first a little easy and work up to where you feel you can handle the bike and the bar.
A little scraping is ok. Just be aware of the road surface features.
Problems? Like dragging the bars and bending them? Yep, done that (didn't go down though). I put about 10,000 miles on w/o a problem and no problem on winding roads. In my case, I turned on a city street and leaned into a bump/rising pavement in the dark. There are a few others who have scraped them or crashed, but I think it is usually in very tight curves or unusual pavement. I'm not real aggressive, but I do scrape the pegs on ocassion, but have only scraped the bars the one time. I did put Cobras back on my bike, btw. You will find some who have scraped or crashed and you will find some (probably more) who swear by them because it saved the bike or them damage when they dropped the bike or crashed. Something to be aware of, but in overall risk, probably way behind things like left-turners, gravel or deer.
Make sure the bottom of the bars are pulled as far forward as you can possibly get them when you are tightening them up.There is a small amount of adjusability there.If they aren't forward....changing the oil filter is a PITA.