There are a number of labs around the world offering alternative services to dr5 but at a low level of through put, or alongside volumes of motion picture processing. In general they aren't interested in handling the odd few films from individuals and can't handle all formats anyway.
dr5 is currently the only lab who offer a realistic, dedicated B&W reversal service across formats, and with good knowledge of a wide range of films. I'm currently working with a London based lab who may begin offering a limited service next year, but they aren't interested in providing the kind of all round service David offers there's just not enough demand. They have 2 or 3 clients interested who need a fast 24hr max turnaround for commercial reasons.
It's highly unlikely anyone else will be prepared to invest the money required for research & equipment to compete with dr5, there's more users of Kodachrome than B&W reversal and that only needs one lab for worlwide processing.