I have used replacer on occasion and have never had a problem with it, certainly never lost a kid to it.
That being said, I do try to keep babies on straight goats' milk for at least three weeks-nothing is better than the real thing
I have also been told that there is very little nutritional value in the milk you buy at the store; it barely resembles the raw form.
The other benefit of replacer is that it's formulated to more closely resemble doe/ewe milk. The components are not in the same balance. You should NEVER NEVER NEVER feed calf milk replacer to a baby goat. This is the only time I've ever heard of people having real problems.
That's one reason we have chosen not to pastuerize milk for our kids (goat kids) (a WHOLE 'nother can of worms).
I would be more inclined to buy replacer for a # of reasons:
1. More cost effective
2. Doesn't spoil (within reason)
3. You can alter the compostion (less water=denser nutrition)
4. Doesn't require refridgeration
5. Can make a single serving-no storage
But that's me. Everyone has their own management systems.
If the baby is in good flesh and has no underlying health concerns, I would think that EITHER ONE YOU CHOOSE would be just fine.
Of course, if you want to pay overnight shipping, I'll send you some of the real thing.