The back edge profile of any fiberglass or carbone blades can be modified with the right tools to fit any foot pockets ie. insert deep enough. Location of angle on the blade vs the angle in the foot pockets can be a sticking point but is normally ok if the angle on the carbon blades is not too sharp, rather a curve as with the Speardiver blades. In this case the foot pocket tendons will bend to accommodate the angle in the blades even if they're somewhat offset. That's pretty much all the difficulty you'll encounter with new blades as they should not come predrilled, and you can make screw holes in the blade exactly to match the location of the screw holes in the foot pockets. Screw holes tend to weaken the blade at that point and need to be made carefully. If a blade already has screw holes they will not normally match any holes in the foot pockets other than the ones they were created for. But they will be close, so making additional screw holes too close to existing ones may weaken the blade to point of failure.
DiveR blades do have a sharp built in angle. And the fiberglass version is not all that durable. A customer brought in this broken DiveR fin just the other day and switched out to carbon blades. Nowadays fiberglass blades don't make sense, a good carbon blade is faster, more efficient and more durable. Think like when you want to break a piece of metal, you start bending it back and forth until it weakens and finally gives out. This happens with plastic and fiberglass, but not with well made carbon fiber blades, they will last a million flex cycles without weakening if not abused. It's just the nature of the material.
