We have a 15 foot fireplace (1960's monstrosity which is on the list of things to get rid of!), Jack fell last summer and split his head open on it - very scary - could see his skull, 999 etc etc. Fortunately he was fine, but will be scarred for life.
Anyway, because of the position/size of ours I couldn't find a guard that would work, so I bought 8 cheap cushions and just laid them over the hearth. And after a couple of days of the kids throwing them round the room they've completely ignored them! They work perfectly (and have saved us on a couple of occasions!)
Worth a try?? Look a lot more pleasing also!