Sounds quite easy, if one is willing to go to the main counter.

What was your experience with St. Barth Commuter?  Worth the extra money?

On the return from my June trip I successfully negotiated the refund of $60 in departure tax ($30 x 2 people) by American Airlines.  Given the hints on the St Barth Dental Association website, the information gleaned from the airport website, information gathered here, the alignment of the planets, the phase of the moon, and the total absence of a line of people behind me, I decided that it was time to "go to the mattresses".  I was having difficulty in convincing the counter agent that I owed no tax, but gave her sufficient information (in transit both on my way into SXM on AA and out of SXM on AA, haven't spent 24 hours in-country, etc.) that when she spoke with a supervisor she was instructed to refund the money. 

For documentation I had my Winair e-ticket printout, my AA e-ticket printout, and the stubs from that day's SXM Immigration forms.  Oddly, the fact that I had paid a departure tax from SBH (noted on my Winair e-ticket) seemed to carry some weight with the counter agent.  One of the agent's arguments was that "nobody else asks for a refund".  My reply was that perhaps the others don't know the departure tax rules as well as I do, and they should be asking for a refund - but I know the rules, had not spent 24 hours on SXM, and was due a refund.  "Polite but firm" won the day.

The whole process took about 10 minutes from the start of the discussion to cash in my hand. 

Perhaps Greg ran into the agent who I had already "softened up", or perhaps we're all behind the curve here, others have been getting their rightful refunds for years, and we're just finding out about it.

As to SBH Commuter - I've only flown them as a charter, but I know others who fly them as a scheduled flight.  Put a yellow ribbon (or one of their flourescent green/yellow baggage tags) on your bag, and they will pull your lugage for you - no need to engage SBH Services, no need to clear immigration, go straight to the transit gate.  If your SXM flights match their 1-a-day schedule then it is a great deal.