Probably wasn't any reason to change the pin presses. Hopefully that'll work out for you though.
Don't get to caught up in progression on the plate raises, as that can be dangerous. You're probably doing too many total reps as it is. Do not do them with straight arms by the way. Bend you arms with your elbow at your side and the plate in front of you like you're driving a race car. Then raise it up to around forehead level with your arms remaining bent. This will probalby allow more weight and be better for your shoulders as it doesn't place the front delts in a pre-stretched postion which will tend to want to pull on the joint. The way I've described, if you are not already doing it, may make it easier to progress.
Try to give yourself room to progress on everything. Don't start out with more sets, start out with less even if that means more weight. You could have started with 2 sets of 8 or so on the tri extensions and built on that thus giving your elbows more chance to get used to it. That would be more logical than introducing external support just to do more workload. Your joints have to get strong: they are like a foundation. It would make no sense to dwell on you roof (the muscles) while your foundation is crumbling and likewise it would make sense to make the foundation strong in the first place instead of propping it up while inceasing the load on it.
I think you gave up too fast on GHR's. Oh well
