There is only one person who decides if or when any suggestion makes it to mIRC, and thats Khaled. He reads all suggestions, and does occasionally comment that something is on his "list". There is no public to-do list. As for giving them a rating of some kind, that would be hard to do i think. Something may be on his mind now, but something else comes up ahead of it... or something mucks something else up...and there goes the rating system. He would end up spending half his time updating a to-do list for the public, changing ratings on the fly, and fielding "but why didnt you.... you said you would....." Since Khaled is the only coder, no one else could be doing that for him.
I think if you read thru versions txts, you can see that he implements suggestions from users. As for appreciating the input, well... he did put Features and Developers here, which i think shows he wants and values the input.