I am not in your due date (july), but i will explain why we are choosing to get it done. FWIW, we also don't vax, also don't do eye goop, Vit K, and are having a homebirth. But I see the PKU as non-invasive. You are not physically injecting them with who-knows-what, you are testing them for many different diseases. By 2 weeks, the test is extremely accurate, because your baby has had plenty of time to metabolize your breastmilk, so God forbid there is anything wrong, it will be pretty clear. The diseases they are tested for are incredibly rare, but PKU for instance, untreated can lead to mental retardation. It is for this reason that we also choose to have our children lead tested. We live in a house built in 1870, and know for a fact that there are several areas of lead paint. It is not fun to do, but wouldn't you know my daughter ended up having a higher level of lead in her blood at about 18 months old. It is better now, but I am not sure what would have happened if we hadn't found that out. For us, the bottom line is like vaxes: risk of the disease (in this case, something like PKU) vs risk of the tests. The risks of vaxes are too great for us to consider giving them to our children. We feel the risks of those diseases we are supposed to be vaxed against are much less than the vaxes themselves. Thus, we don't vax. The risk of the blood draw for us is much less than if we our children had one of those diseases it tests for, and we didn't know it.
If you do decide to go for it, there are several techniques for keeping it as painless as possible, such as warming the foot in a wet, warm diaper first, using special lancets, etc. You should be able to request any accomodations you want. You could also nurse during the procedure as well. Anyway, that was a book! Hope this helps!