So, if I send merit points to another user it will be deduced from my account? Most of bitcoiners are holder by nature I don't think they will spend their points even if they cross a good post ( maybe they will do if you pay them well 
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It will be hard for moderators to check all members posts if they ask for their merit points (10 constructive posts), it would be better to use a Demerit system to punish shitposters.
Yes I agree with you. It better to have also demerit system so that it can minimises too the shitposters instead raise the very useful post and constructive, )It will be hard for moderators to check all members posts if they ask for their merit points (10 constructive posts), it would be better to use a Demerit system to punish shitposters.
I think that biggest problem of this merit system is that a lot of people is not using it. They simply ignore it.
Could visibility be increased changing the "+merit" color?
The merit system have been designed few days ago. Some of the members are not even going back online since this system was implemented. Sooner, people will get used to it. And if there are things like ignoring the merit system and ignoring the posts (even the constructive one), they won't be benefited for not doing that and that means that they are the type of people who doesn't want to embrace the new change. This new system teaches us to have a constructive post, and be open minded and teaches us to give those posts the merit they deserve.
..... All is well but we must also give the opportunity to the new to go up in grade...
That's why you have no merit requirement up to junior level and only 10 for a member. Highest ranks are supposed to be hard to achieve. The previous system based on activity was way too easy.
I hope the new highest rank is introduced, so all the current Legendaries have something to strive for.
I think that biggest problem of this merit system is that a lot of people is not using it. They simply ignore it.
Could visibility be increased changing the "+merit" color?
Not sure whether people ignore it, or just waiting to see how this system will pan out. You don't want to shoot yourself out in the first week.
But changing colour is a great idea, green should do the trick.
+ Having sMerit balance shown on the Merit summary page would be useful (not visible for everyone though)