The solo portion was for the actual descent to depth. The support divers were present to deal with decompression logistics. Heck, if you follow the logic of not "solo", then the record dives of GI3 and J. Jablonski would follow the same frame of mind. They, too, had support divers on their record penetrations at Wakulla. One of their divers is an instructor at the shop that I used to teach at. His portion of being a support diver on the record penetration required him to have a deco obligation of over 4 hours. Yeah, he didn't lay any new line, but they wouldn't/couldn't have made their dives without highly competent support divers.
To make dives of this nature without support divers would be akin to traveling into space without ground support.
While I personally dive Mares regs, I'm going to agree with Zombie in that most any high end reg would have been sufficient for this dive. The mix that was used would be the equivalent of diving to around 250' or less on air regarding the density of the gas mix.
Dives of this nature are extremely hazardous due to decompression issues. Even though they are literally bounce dives in nature, the pressure gradients are such that M values are often exceeded resulting in the high possibility of hits throughout the deco schedule. I have heard conflicting reports on whether or not the RGBM was utilized in this dive. I would be interested in seeing the run tables for its execution.
Greg Barlow
Former Science Editor for Rodale's Scuba Diving Magazine