I can't speak on the community standards side of things as I don't know what or if there are a specific set of standards for steemit development. I do however know this type of system works very well on slack. In terms of implementing I can't say I know the specific inner workings of the steemit platform - but I assume its a combination of php, sql, and blockchain tech. From the php/sql side of things it would be incredibly easy. Its a matter of setting the rep score as a variable and then running an if check on it.
$rep = functions_to_get_rep();
if ($rep > 5) {
//functions for user
}
if ($rep > 25) {
//functions for user
}
In terms of the paid features I suggested, yes this would take a bit more work. A series of flags that store features an account holder has paid for - and then of course creating functions for what each said means.
I don't expect it would happen overnight - or even that every (or any) feature I recommend would even be created. But I hope it will instill some outside of the box thinking on ways to solve some of the problems I have read about and experienced as well as give some thought as to ways to increase the overall value of steem.