I never used a Dyron lens, but heard good things about them.
I use a SubSee +10 on my Nauticam Panasonic LX-100 rig and it works great but is picky about micro unsharp because of camera movement
As tronger the lens is more you need you need very good buoyancy, a lot of light and calm water to archieve sharp shots.
Also a focus light to help your autofocus to focus on the right point as DOF is very limited.
Shoot F16 and at least 1/250sec to obtain sharp images
If you can get it for a very good price then buy it, otherwise opt for a less strong lens
Try it first on your camera/housing combination to see how much zoom you need to get sharp images and elimiate vigneting