Any useful comparison is only relevant when considered against the type of the teams, league and referees involved.
Where you have a league with a high number of poorly disciplined teams, the referees getting the good club marks are likely to be those who are not applying the LOTG correctly whereas those referees who do the job properly are likely to upset the teams and get a correspondingly low club mark.
Any system which is used to make judgments on someone's performance, must be robust and transparent. Club marks are neither.
Teams are not made to justify their reasons for marking below standard, unless they drop below a set point......if the mark isn't 70-75 teams should be made to justify why it isn't and that equally applies to anything above that line.
This, for me, would be the simplest change that would have the biggest benefit....it would stop the vindictive or ignorance based low scores because a judgement would be able to be made as to whether the low, or high, mark was valid. It would also enable prompt feedback to be given to the ref....
Nor is it particularly transparent....many leagues don't reveal to referees what their club marks are.
Also, it's easily manipulated.....every refs sec knows the teams that always score well so it would be simple to stick a particular ref on a few of their games to bump up their average to secure a final appointment......and it does happen.
Just the same as you see certain promotion seeking refs kept away from 'problem' teams over the course of a season......