The way rep works is there is a check if your rep is higher than targets, if so, then it subtracts rshares from the target's raw rep number.
SP isn't factored into it until the first check (if rep higher) passes.
Rep, in theory, can't be bought and takes time to develop, and is more meaningful metric than Steem Power when adjusting the rep of others, but in practice, rep is easily gained up or down and virtually meaningless when it can be bought from bots with no actual costs to users.
In a nutshell, rep is busted big time and virtually useless.