He lost in convenience and comfort what it gains in safety and on this side, I made my choice.
In use my 5 year old daughter no one complains very little and very occasionally because the module to be added to the child to fasten the seat belt sometimes squeezes her stomach when she wriggles. Beyond this small inconvenience, nothing to report except the assumed stress of managing this module and the belt must be attached when the child (it's less convenient than solidarity harness seat).