I'd considered a roll bar for my previous 4/4 and was about to ask Williams to fit one. Luckily I tried sitting in a customers car with one fitted and found that my head came perilously close to it. Fine for competition wearing a helmet but in a road shunt could do serious harm not good.
The Librands one sits lower and further back so that aspect isn't an issue although how effective it is in a rollover I'm not sure. It does stiffen up the chassis though.
