I just returned from St Lucia January 8th. Prior to leaving I contacted via e-mail numerous dive shops, and had selected Dive Fair Helen - They were absolutely the right choice.
We stayed at the Caribbean Jewel in Rodney Bay (great hotel). In the north side of the island, they're are numerous dive ops Frogs, Buddies, Sandals etc. Dive Fair Helen is located in Marigot Bay. I met about a dozen divers during my two weeks on the island, so I got a fairly large sampling of dive experiences.
Note - All of St Lucia requires Dive op supervised dives, no glove, no knife. That makes it critical to choose the right dive op.
Frogs seemed to be the worst - 34 and 41 min bottom times, small boats, and aborted trips to the Pitons.
Buddies comments were "ok, but I wouldn't use them again.
Resort dive ops - "Made me do an orientation (beginner) dive even though I am a rescue diver". "20 people on the boat-crowded diving" "short bottom time (30-40 min range)
Note: If the dive boat leaves from Rodney Bay or Castries, it is almost a 1 1/2 hour trip down to the best diving spots in the south of the island. Dive Fair Helen picks you up at the hote, about a 20 min ride to boat, then 10 to 15 mins to the best dive spots.
Owner of Dive Fair Helen - Andre - is a Marine Researcher, and is constantly reviewing the best dive sites for the weeks based on current conditions, not historical. Difference was that when describing my dive conditions, other diver's were envious of the dive experience. Also, if you happen to be a diver who cares about local marine conditions, impacts on the marine life, as well as a detailed knowledge of local marine life, Andre is a fountain of knowledge.
As for the way he conducts his dive ops - 6 to 12 max divers (resorts had up to 20 divers on a boat), bottom time is determined by your own consumption rate. You do not have to surface when the group air-hog runs out of air. Air Hog goes to surface, boat picks them up, and you never are interuppted. His dive instructors are trained to allow experienced divers to fully enjoy their dives. Other than a deep dive, I averaged 54 mins bottome time with one 62 min. FYI one of the dive instructors, Chris, is a SAC FREAK!. Consistently came up with over 2000 psi after every dive!!
Boats - modern and in excellent condition, 1 medium, two large boats. Very comfortable cruising.
Food - Andre's wife cooks the food every morning. The Fried Chicken, Rice and salads are some of the best dive boat food I have ever experienced.
Equipment - I bring my own equipment, but I did take a look at the rentals offered - all mares, medium range, good condition. You can leave your gear at the dive shop in a secure lock-up.
Also, Andre will arrange for your own private dives based on your requests - I wanted to do a wreck penetration without having several divers moving around - no problem, We did the wreck first drop, while every one else did a drift dive. 56 mins to thoroughly explore the wreck on my own. Andre showed me around the wreck and led me through the penetration once, after that he moved off the wreck, and it was all my own.
Water temp on every dive was 81 surface and 81 bottom (112 feet) except for on thermal that dropped it to 79.
Hope this helps.