I think that it would be beneficial to have a chance for the target of an anonymous hit to find out who it is that post the hit against them. 

By doing this you add some potential risk and accountability to posting an anon hit. If you are going to post a hit against a heavy hitter you take a chance that they may find out and take retribution. 

In my opinion not only is this more realistic (in real life if you post a hit against a mob boss there is at least a chance that they are going to hear about it) but also can add a chance of accountability for those that are putting massive anon hits against people as a way of grinding an old axe knowing that they can't be definitively linked to it.

To keep it more realistic I think you could make the chance of discovery go up based on the targets level or maybe their street smarts. I would recommend leaving even the highest chance relatively low (say 5-10%) but I think even that would add an interesting element to the hitlist.