Highly recommend BVIYC
I've chartered a total of 4 weeks with BVIYC -- two Beneteu 44s, and most recently (feb 2009) Isle Dance (Ben 46) and Mistral (Ben 50) back to back (yes, 16 days at sail). I have sailed twice with TMM, and consider them a good company, would sail with them again, but BVIYC is first choice.
Their service is over the top -- they maintain their boats well and are devoted to client satisfaction. They sent a mainsl batten from Road harbor to Marina Cay within hours -- accomodating our schedule which included time at the Baths before mooring at Marina Cay late afternoon on a saturday. Anthony is head of their service and can talk you through any topic -- corroded starter cables, windlass glitches, anything that came up, any hour of the day.
Their location at Port Purcell also is very easy access to Road Harbor, in or out. TMM and others on the west side of the harbor can have some tricky passages through shoals. Port Purcell is a piece of cake, and is 5 minutes walk to provision.
I can't imagine any disappointments with BVIYC.