I have always used bark busters, but have stayed away from the plastic hand guards (except for supermoto and winter riding), but I generally like to separate myself from the bike in the event of crashing. I have never had an issue with getting caught in them and they have saved my hands and controls on many occasions. Sometimes I hit saplings or pylons intentionally.
I do know someone, that is/was on this forum that did end up breaking his arm that way when he went over the bars. But I would still recommend them along with a wrap around skid plate, Radiator braces/guards and pipe protector if 2 stroke.