Very tough on rugby players to front squat with various injuries that is why the front squat harness is fantastic for them also the safety bar which has a similar feel with out the issues of lack of flexibility, I have had some players go to 140kg on the front squat harness, we use it to teach catch position for cleans and also to build confidence in that whatever you can clean you can stand up with if you are front squatting 20% more at least, so having a strength differential is important between the 2 movements, cheers,ash