In order to ship wood it has to be kiln dried,it will always have less flavor, I'm sure they are several methods to dry wood, max temp/time will all play a roll as to the final outcome. Shipping bugs all over the states is a no no and go by any camp site and you will see signs about bringing wood from other places , local wood is always preferred but not always available.
I always use Weber wood chunks and have never had to use more than 2 in my 18.5, usually i'm fine with just 1. I first used pecan when i got my WSM as i had a chart indicating it was good on all meats but everything was over-smoked. finally switched to a bag of weber apple chunks and my chuck roast was perfection.
I've used the Western Premium brand from Walmart, which I assume is the brand you are using, but I use a mix of mesquite and either cherry or apple. I always get plenty of smoke flavor. I also use the Weber branded wood and have had good results. Being in Oklahoma everyone uses hickory but I prefer mesquite and I think folks like my BBQ because it's a different flavor than most other BBQ around here. My wife actually doesn't like a heavy smoke flavor so I usually add just enough wood to throw heavy smoke for the first hour or so. But, this WSM of mine pumps out smoke for the whole cook no matter how much wood I seem to use.
So, reading this thread made me wonder about something. Have any of you mixed pellets in with your charcoal on a WSM cook? I've been contemplating doing that instead of chunks and would like to hear opinions on that.