front struts are coil over anyway, so never really understood the name but, setting them apart from most OE set-ups, they typically use much narrower 2.25" springs.
object is in improving ride/handling compromise, as any other spring/damper change. some will have adjustable platforms, allowing you to adjust ride height whilst unit is still in-situ
PS. are Clio rear coil overs actually 'coil over'?