Haven't done St Lucia to St Vincent and Grenadines. I was thinking about either the st Lucia to Grenada one way or return trip from St Vincent. I have done to charters in the Grenadines both out of Grenada.

The big difference is the length of sail (from St Lucia and the Pitons to Bequia or Grenada St Gorge to Carriacou (first island in the Grenadines chain from Grenada). Regardless of where you start you will have a long sail to get to where you want to go. Once you get to the Grenadines sail distance is more aligned with what you are used to in the BVIs. ALso if you do the one -way you will also have a long sail from Carriacou to St George and the Port Louis Marina.

Sailing conditions would be similar with strong trade winds from the east generally. more current than what you would expect in the BVIs and SFD channel as the Atlantic flows into the Caribbean through the island passages.

Most islands will not be as refined as you would get in the BVIs where there is a great bar or restaurant it seems in every harbour/island. Having said that Bequia is supposed to be beautiful and well worth two nights, Mayreau, Salt Whistle Bay is one of my absolute favorite beaches and bays. If you want swanky you can stop for the day at Palm island if they have room on a day pass which includes lunch and all you can drink ($$$$$) or stop by Petit St. Vincent for dinner at the beach restaurant. Chatham Bay is also a nice relaxing spot. Union is take it or leave it but you will have to stop by to check out so, stop by Happy island and enjoy.

Boat boys are not that big of a deal. We always chatted with them, offered them a beer or a coke, give them $10 ec if they helped with a mooring or guided us to a particular anchorage spot. If you ask them to get you something make sure you are clear on the price! Do not buy ice from Tiger (boat boy at union) he charges you 4x what you can get it for at the local marina! Also if you are heading into Union, and you see a boat boy frantically waving you off a particular route, you might think you are going to run aground, in reality he just wants to guide you to his Mooring ball and charge you $60EC for two hour use... didn't make that mistake twice!

I am sure you will love it but it is more of an adventure than BVIs!