I think the default network is pretty solid now. If anyone leaves some questionable feedback it is openly dealt with here in meta. I just think that the scores are too high and will give newbies a false sence of security. If you are new and see some guy with a +10 trust score you assume he is trusted... I think the new formula is alright just the numbers are too high.
Again, an high dark green trust score doesn't mean that the user is pretty "trusted"... everyone should (always) trade with his own diligence. Now this little modification of the trust system will be evaluated in the next few months/years. If someone 'can' suggest a new better thing I think theymos will modify the system another time.