Not to really put a damper on things but this would put anyone who wants to use a devil fruit at an extreme disadvantage in the beginning because they'd have to reach level three before technically being able to use it. That causes a lot of issues with a lot of members characters. Not to mention the way it's set up the only people who can really surpass level three are devil fruit users which would put non devil fruit users in danger later. It really isn't fair for anyone and would probably end in feuding between members and other such things.
If you really want to make it effective you'd have to make it a LOT more detailed through out but I still don't think Admin-sama would like it very much. (I'm considering in the comment he made earlier in this calculation as well)
Besides in the long run this would be no different than the bounty system already on the site and in my opinion that system seems a trifle bit easier to understand.