The only drawback IMO with sidemount is your wider. I dove manifolded 95's for 4 years . The weight dragging em in and out of the house, truck and fill tank seemed to invite injury eventually. The isolator is the achilles heel inwhich a leak there would deplete both tanks. Valves behind your head are OK, but under your arms is better. You may have to make 2 trips to and from the water without a cart but I carry the first one down on the initial site evaluation so Im walking down there anyway twice. I have 2 independent systems, each with 1st and 2nd stage, SPG and wing inflator. I dive a dual Nomad for redundant lift but only connect the one on the left tank and leave the right lp inflator tucked . No problem with routing on regs with a bit of experimenting you can get angles of hoses correct. I like long hose on left tank, behind my neck and in from the right side. Right reg on bungeed shorthose comes over right shoulder and has a hard 90 degree. SPG angle can be a challenge depending on where you want em to be. I clip mine in so they lay flat against my chest. VIP's are cheaper. No labor for tearing down and setting back up. Some may say having to change regs every few hundred PSI is a drawback to remain balanced but I dont find it to be a problem at all. On a rec dive boat I prefer an aluminum 80, but with a wide enough ladder, getting onboard with tanks attached is fairly easy and giant striding into the water does fine. Easy to feather a bad reg, easy to detect and shutdown a bad reg, bubble checking yourself is easy, the good far out weighs the bad.