While I used to dive double steel 98's prior to the rebreather, I never did so without backup flotation. The drysuit is my first choice, oral inflation of the wing (bladder not compromised) being my second choice, but a LB makes a good third alternative. As stated above, the LB must have a top mounted dump, and you will want to attach the strap low on your body around the waist area, so that the top of the bag is accessible to you (keeping it close to the chest area for control). The best way to utilize the LB for flotation is to only get put enough gas in it to still require a slight swim up, dumping gas as you go. You do not want to fill it to where it starts floating you in the water column, because it will very easily accelerate past the ability to dump gas fast enough. You have to stay ahead of it, and swim up.
I use a Halcyon Closed Circuit LB so that there is no chance of inadvertantly spilling the gas at the surface and decending like a rock again. This could have dire consequences. I have swum up some heavy stainless hardare using my bag and deflating my wing completely. It takes practice to do this safely, so if you choose to go this route, practice it as a skill on a shallow dive so you are aware of what will happen when the skill is really needed.
A few months ago on a trip to Bonaire, I watched a guys inflator come clean off the corregated hose, leaving his wing unuseable even via oral inflation. Luckily, he could swim the rig up, as it was just a simple recreational setup. If we had been deeper with doubles, he would have been in trouble with a some sort of backup.
I use a Halcyon Closed Circuit LB so that there is no chance of inadvertantly spilling the gas at the surface and decending like a rock again. This could have dire consequences. I have swum up some heavy stainless hardare using my bag and deflating my wing completely. It takes practice to do this safely, so if you choose to go this route, practice it as a skill on a shallow dive so you are aware of what will happen when the skill is really needed.
A few months ago on a trip to Bonaire, I watched a guys inflator come clean off the corregated hose, leaving his wing unuseable even via oral inflation. Luckily, he could swim the rig up, as it was just a simple recreational setup. If we had been deeper with doubles, he would have been in trouble with a some sort of backup.