Hey Ed and god,
I apologize if you misunderstood

and if you feel offended

, that was not my intention.

I was just trying to understand (A) what specifically is the issue (Ed has at least addressed that) and (B) avoid someone just making a comment without providing specifics.
We all have our own experiences which is what makes topical forums interesting, but only if we can share the details vs general comments so we all can learn.
Now, if they leak (I'll take your words for it as I have not experienced that) why do we see them on so many industrial / commercial buildings (at least in my area)? Why do we have so many retailers, including the big box stores sell them? I would think if they leak so much and stop working after a while that there would be an uproar against them, the retailers would be getting constant returns (which does the retailers no good), and so on.
If you had links to specific consumer reports, etc. that would also be great. I did a google search and could not come up with any. I did find this
http://www.askthebuilder.com/442_Roo...ne_Vents.shtml from a gentleman with (per his web site) similar amount of experience who says they are wonderful
Again, I am not doubting your vast experience, knowledge, and so on......I'm just trying to understand the details of all this so we can all benefit.
Many thanks!