I cooked two butts last night, one for me and one for a friend (I swear Ma! I'm not smoking butts, I was holding it for a 'friend'). I took the opportunity to test out Grendeddy Dave's on my pork butt so I could compare it to the other one.
The BGE held steady at 250f overnight, as usual. Here's the log. When I re-read the weather column this afternoon, I started laughing. I totally forgot I did that.

5pm - cool, raining
6pm - rain
7pm - rain
8pm - more rain
9pm - building ark
10pm - collecting animals 2x2
11pm - pigs reluctant to get on board
12am - pigs consulting with big bad wolf on ark destruction techniques
I only had one working remote probe thermometer last night so I put it in the smaller butt*. Once it hit the target temp and it came off to rest, I switched the probe to the larger butt. That's why the temp changes drastically at 5am.
So both butts were cooked relatively the same so here are my opinions.
Grendeddy Dave's Hawg Rub: I wanted to like it. It has a nice aroma and gives a nice appearance. But every bite I had, the flavor of celery hit me. I guessed they used celery salt but it was actually celery seed. Either way, it was not a hit in my book.
Grendeddy Dave's Hawgwash: Loved it, loved it. This is an Eastern NC vinegar type sauce and it punched me in the mouth with heat and sweet. It tasted great on meat from either batch. I will definitely be getting this again. It's one of my favorite commercial sauces for pulled pork that I've ever had. It might be a good mop on chicken too.

*Reminds me of a funny joke, What's the difference between an oral and rectal thermometer? Leave your guesses about the punch line in the comments section and I'll post the answer later this week!