As my blood type is O-, I'm rather popular with the Red Cross and they talked me into doing a double blood donation on Friday. I have gone through apherisis previously, but had a massive case of the tingles because of a reaction to the the anti-coagulate. The new process doesn't use any were near as much anti-coagulate because there is only two cycles were they are pumping fluids back into. I still had to hit the Tums pretty hard (nine tablets) but it was manageable.
One particularly interesting aspect of the new method of a double blood donation is all the saline they pump into you. While I did look a little pale the rest of the day, I felt particularly good and several people commented that I had bright eyes.