Suspension seats all the way for me. I've been involved with many discussions on suspension versus tub and have been involved with off-road racing for many years. I'm friends with quite a few of the SCORE and BITD racers and the majority of us prefer suspension. There are a few that argue the points you've listed, but the same argument can be made that the tub seats have no give and transfer 100% of the impact to the spine. I've ridden in trophy trucks with suspension and tub seats and can say that the ride in the suspension seats was less jarring to me.
The pro-tub crowd's argument is that the suspension seats allow you to move downward on impact from a jump, then the seat sudden'y stops your acceleration abruptly, causing the spine injury. Hey, forces are forces and unless the laws of physics have been modified, and abrupt stop to the spine whether at the end of a suspension seat's sag or at the sudden stop of the tub, they forces will be the same. And have you sat in a tub seat for a few hundred miles? I have...no fun, I won't do it again.
The pro of a tub seat is that you can cinch down on the seatbelts and get no movement out of the body whereas you still will have a little movement on a suspension seat and the tub seats usually cost quite a bit less than a good quality suspension seat. The con of the tub seat is it transmits every bump, every shock to your body. And over a long race, will fatigue the heck out of you. The suspension seat absorbs some of the small stuff.
Go to a SCORE race and ask Robby Pierce, Bj Baldwin, Pistol Pete Sohren, Rich Klein (Lil Rich), and others. You'll get an overwhelming response from most of them, suspension seats are the way to go. But the caveat is, you better choose a good one though. A cheap suspension seat is much worse than a tub seat any day.
Bottom line though, you need to decide what kind of driving you will do. Are you building a SCORE legal competition vehicle. Or are you sandduning, or trail-riding...
Arctic Cat Prowler Desert Race XTZ: ITP BajaCross tires on ITP Beadlocks, Beard Super TZ Seats, Crowe 5pt harnesses, King Off-Road Racing Shocks, Custom Racing Chassis with 7 inch longer wheelbase, +5 Suspension set at 16 Front and 17 inches Rear inches travel, UTVINC did the tube bending
TEAM PROWLER NATION...