I didn't read through this whole thread, just going to post my thoughts, so if this has already been said, my bad.
If it's real human grade enanthate or cypionate, it shouldn't hurt at all. I don't care how rough you are with the injection, even if you move the needle around a little bit it should not hurt.
Human grade sust, it should not hurt either, unless you happen to be sensitive to the propinate ester. So the same can be said for human grade prop.