So we followed their advice. We initially tried the Latex (rubber) NUK Orthodontic nipple; our baby took to it right away. His speed of sucking was not very efficient in the beginning (sometimes it would take an hour to finish two ounces!), but we kept working at it and he is now starting to do quite well... He is sometimes able to finish 2 ounces in only 5 minutes! My husband would give him one bottle each day and it seemed frequent enough, that over time we began to see a learning curve developing. Yes, it did take some patience--but it eventually worked!
...Then our friends suggested we try the Gerber NUK Orthodontic Nipple. They explained that after having similar problems with their daughter, they went out and bought several types of bottles/nipples; the NUK brand worked the best by far.
Now that our son seems adapted to the bottle we have tried the Silicone version of Gerber's NUK Orthodontic Nipple as well. I would not suggest Silicone in the beginning if you are having problems, as Latex is much softer. But once the baby has adapted to the concept, the Silicon NUK is more durable (Latex can be a choking hazard, as with time it disintegrates).
The price of Gerber NUK Orthodontic Nipples also can't be beat--the nipples themselves cost around $3.00 for two. The price for the corresponding Gerber brand nursers (although in truth, any generic bottle would work fine with these nipples) is only $3.00 for three "Fashion Tint" Gerber nursers. Really--who can beat a price of $1.00 per bottle? (A side note: the Gerber nursers do come with nipples already, but they are not the Orthodontic style and so our son would not take them.)