Finally tried Weber charcoal, exclusively, in my 14.5" WSM, and I thought they did fairly well until a rainstorm hit us and knocked the temp down 100 degrees. (300° to 200°). I had problems getting the temp back up so I refueled the bowl with another 10 briquettes.
For what it's worth, I smoked two chickens (partial minion method - for lack of better words), including a few dogs and sausages. Foiled the water pan, but no H2O. Flavor-wise, the birds (organic) tasted very well, and so did the rest.
Not sure if these coals will last as long as some have said until I do a long butt smoke. I like the aroma though, and I can see myself stocking up on these if the price drops a bit more.
I'll be grilling burgers, tomorrow, so we'll see how hot the coals get.