The GoPro is compact and sturdy. It's going to be safe, specially if you are aware of it when you jump in.
For instance, if the best and safest way to enter any given dive is a giant stride, then:
1. Inflate you BC.
2. Hold the camera in left hand, extend arm all the way up above your head.
3. Keep regulator in mouth and hold it in place with palm of your right wand... finger tips keeping mask in place & looking at horizon....
4. Jump in.
Ask your buddies to report when you get back on the boat and tell you what they saw happened to the GoPro on entry... you will see that it is very likely your camera, which you are holding extended up, did not even get to dip below the surface on entry.
I used to worry a lot about impact cameras take, and the ability of the housing to withstand a rough entry.
If the entry is a back roll, similarly, just tuck the housing in your belly and roll back, let the tank soften the blow.
With an SLR, you can use the same entry techniques. You will have less issues doing this, as compared to asking a crew member to hand over a camera after you jump in.
Things happen on dive boats, it's rought as you all know, and it has been my personal experience that more often than not, I will notice a broken fiber optic cable, or a clamp is loose, or the filter got deeply scratched, or the light has no more juice from being on during an interval, or the memory is full from taping a full hour of "Camera Bucket" and guess what... .Its been my fault because I left the camera out of my orbit of control, it got moved, rolled over here or there and I was not paying attention.
Asking a crew member to hand a camera over is stressful to them, if they pick it up the wrong way, or lift it by a fiber optic cable, you won't notice until you are firing the system up and it's too late.
Beware of the camera bucket. If you have full possession of the bucket, e.i. No one else onboard has a camera, go for it. As soon as there is company, your camera is going to endure a UL Testing, just like putting it in a washing machine, the more cameras go in, the more dings, scratches and damages you will exchange with other photo and video enthusiasts.
I've had a red filter break off one of my GoPro housings from just letting my guard down, and from blinking and later seeing my system taking a jacuzzi dip with other rigs in a bucket.
So in summary, trust your controlled entry skills. Practice if you can, avoid loosing control of where your camera is at any given time, and use the bucket if you are able to claim full and sole use.
Cheers.