You were lucky that GB left on time for you!! And with most people that is probably the case. However we had to wait a long time at the airport (they were waiting for others and for departure. (We left over 45min late as they were waiting for more people they knew) So you just never know! We have never had a problem getting a seat on the public ferry. They seem to count it out just right! But weekends can be busy as locals go back and forth between the islands. My husband is very sensitive to diesel and I tend to get motion sick as well but have never had an issue with the smell on the boats. The boats now are nice- one even had a movie playing while we crossed! We have had plenty of room and for the price we are more than happy. Some say it is easier with GB but we didn't find that the case either. They took our passports and we had to keep asking for them back, not sure why it took so long. In Marigot they check your passport, write the number down and you get it right back. Very easy to get checked in, then have a drink while you wait for the ferry. We usually fill out our immigration paper while waiting. On the GB we had to have all of that done before the boat left the dock. For some using GB will save them a taxi to Marigot but the ride is very quick over the new bridge and you get a quick tour of Marigot- enough for us. Another consideration is that GB takes a deposit to reserve your spot. If something happens and you don't make the boat you loose money. That also happened to us because we had a change of plans. That doesn't happen with the public ferry because you pay as you go. We travel on a budget and while GB is maybe more convenient as far as proximity to the airport, Marigot isn't that far out of the way and we like having the "extra" money to use for meals/drinks! With all this said, again the people at GB were VERY nice especially in dealing with my motion sickness/nervousness. (I found that I do better on a bigger boat than the small motor boat.) The bottom line is that both options will get you to Anguilla!!