By the way...
We used the drop-ins throughout our visit with Grandmom and Granddad. They are Avent brand and use the same nipples as the old, evil bottles. I kind of hate to reward Avent for using bad plastic by buying more of their products, but at least this way I am still using the nipples we already had that Selina likes.
Fortunately, the glass bottles (Evenflo) arrived while we were away and she is okay with those nipples too. She doesn't like them as much as the others, but she doesn't reject them. So we can stick to glass at home and drop-ins on the road.
All is well. I'd recommend either product.