The amount of posts should definitely be raised IMO. I am a member of several other boards and they all have levels of around 400 posts to become "Senior" or whatever they call it..
While it doesn't stop ppl from posting two word replies or banal drivel with every post...it's normally only the small minority that will take advantage of it in that way. A combination of post amounts and AP should be enuff for most of us to see if the person posting is worth listening to .

Going with a complicated system for advancement would probably lead to too many problems...besides...whats the big deal with being a "Senior Member"? It's not like there are monetary benefits or anything like that .

If I were asked for my opinion, raise the amount of posts necessary and leave it at that.

just my 100 pesos worth..