Other than the worry about knocking someone up, there is NO difference whatsoever.
The change in the amount of ejaculate is microscopic, much less than 1%, and not at all decectable.
There is zero change in hormone levels at and therefore no change in libido.
Once again, no change in sensation at all.
The only real change is is that you have zero worry about pregnancy and zero worry about contraception which makes sex easier and more frequent.
All in all, I'd suggest it to anyone.
The only downside is the akwardness of having to jack off into a cup, carry it around with you so that you can drop it off at the lab.