A HUGE advantage for you if you want to run tech trips down your way; It is nearly impossible to get good trimix fills anywhere in the Keys. Shoot, even if you don't end up doing the charters, you'd still have my business just for fills.
Yes, the down line is handy and that is a very good point about the possibility of doing a sand dive. It essentially ruins all dive plans for that day and damn, that gas is expensive. I've been on a boat that hooks in, but still allows drift deco and liked it. They still sent a DM down to tie the buoy in, and the boat did not hook up, it was just a very large buoy and when everyone was ready to drop, the boat brought us slightly upcurrent of it and we swam to the buoy. The DM sometimes would remain at the hook in, and when he counts all divers are down, he'd unhook and ascend. Being secured to the wreck would be advantageous because if there is a bad current, the divers may have to climb down the line and a mushroom anchor would not hold. A chain and snap shackle are normally used. The hot drop is still my favorite, but we have to really trust the captain to judge the current.
Even the larger 46' Newton boats in the Fort Lauderdale area that primarily run rec trips, will limit tech trips to only 6. More than that and it is difficult for the captain to keep track of profiles, particularly if it is a drift deco and not everyone is launching their SMB at the same time. Again, the space thing is another reason they only allow 6 on a boat that would normally hold 24.
Another common contingency is everyone comes to an agreement for bottom time. At a predetermined time, everyone drifts off the wreck, but may not launch a buoy until they hit their 100' stop or something. The captain would have to judge where he thinks he may see the buoy pop and be in that position to follow it. I'm not a huge fan of this procedure. I prefer to launch the SMB as soon as I leave the wreck. That is the procedure for people diving off my boat.