I too donated Bone Marrow, approximately 3 years ago to the day. Mine was the giant needles to hip bone method as well.
The recipient was my Father, so a much different situation, but will offer my 2 cents from a different perspective.
I am a naturally anxious person and chronic over-thinker. The hardest part of this process was the unknown and the guilt associated with that. Having heard of the "pain" associated with the procedure, I was extremely nervous if not somewhat reluctant. I never had any doubt that I would go through with it, but even just the thought of reluctance gave me a feeling of guilt. It was my DAD after all, I was ashamed for even having that thought. It is a very odd feeling to know you would do whatever it takes, yet still have some self doubt in the process. To the OP - Obviously much different when a family member is involved, but just be aware of the emotional side of it as well.
Your procedure sounds much different than the needle in the hip, and from Rygel's description, doesn't seem to have the same "side effects"
From my procedure, I will say knowing what I know now, I wouldn't hesitate to do it again. It is a painful few days, but a manageable pain. If you have ever worked out really hard and had that muscle soreness the next day where you almost couldn't move, its a magnitude of that feeling. Hopefully that will help someone reading this thinking of that procedure.
Always happy to chat about it more, please feel free to PM me. It's such a great thing that I am sure more people would volunteer for if they understood it better.
Saving my Father's life is my proudest moment by far. While I don't think I am a hero by any stretch of the imagination, you are certainly a hero to those who's lives you can save.
Still have yet to take this off: