Hi there. Love Sitka spruce!
Those little epicormic branches are important spare parts for the tree. Leave them if you can. Work around them while climbing.
Dead parts are also important to the tree ecosystem. I recommend making some safety breaks of branches along your route that you might dislodge. Just use your boor or hands to break the branch off leaving a sturdy stub.
To reduce impacts find a good anchor spot and leave a string in the trees you climb often. Pick a route where you can work around the epicormics. Set the rope out from the trunk if you can.
I may be out side the norm saying this...but I strongly urge rec climbers in wild trees to do no pruning with a saw. Leave the tree looking natural!
Like it or not all tree pruning is really for people...not for trees. They are quite capable of pruning themselves.
Hope this helps...I know of some huge Sitka's in OR hope you find more! Scott