I had my first experience with the Henry 663 last night. I must say, I hate it more than the Gardners. It seems to get all over the place and when it does, it is sticky...and stays sticky. After my mistake of not using gloves, I donned my last set and continued (that didn't stop it from gettin on my arms though).
I used the recomended notched spreader but it seemed to use a lot of adhesive. I resorted to grabbing a handful (gloved handful) and spreading it around, then hitting it with the notched spreader.
I asked how much I would need in a different thread. It looks like I will probably use a whole gallon on just the 2 sides. That is a lot more than was suggested.
For the folks who used it, did you go for 100% coverage?
How much did you use?