It's better to donate whole blood then double red cells. When you donate double red cells, they pump your blood liquid back to your body and you don't want it! The reason for this is because it is important to lower volume of blood, blood becomes thicker on TRT, in your body to make it thinner and easier to pump for the heart.
I agree with your answer, but not so much your reasoning.
To my knowledge, there is nothing bad about them pumping the extras back into you, and it may even be slightly beneficial.
The blood pumped back in is free of rbc's, it is thin as can be.
I stick to whole blood because I feel that the more frequent donations keep your hct/hgb at a more consistent level.
While some guys can get by just fine doing double rbc every 4 months, for others doing whole blood every 2 will have a higher impact.
The only time I have ever done double is at my alternate donation center, which I only go to if my levels are higher, and I do it in between donations to get my levels down even further.
At my next dr appt I am just going to get a standardized therapeutic form filled out. One of the centers near me will charge you a small fee if the blood is not usable, while the other will do it for free regardless.
Different places have different guidelines, so it is worth checking into if you have more than one in your area, or there is another one in an area you frequently travel to.