Expanded metal decking is very directional in nature. If you lay it the wrong way, the stuff is slicker than greased snot, and if you put it out on state bid, the contractor will for sure be an idiot and lay it the wrong way. This is especially true if the application involves longer runs where placing the 4 x 8 sheet lengthwise is faster than cutting it in half to place the two resulting 4 x 4 sheets crosswise. The same less cutting and more efficent use of material logic will apply to 4' wide steps, so the contract specifications would need to be very specific.
And I agree there is still the cheese grater factor - when someone does eventually fall for whatever reason, they are going to be more seriosuly injured than if it occured on carpeted wood steps.
Non skid paint works fine, but so would any epoxy finish with sand sprinkled on top of it. You may be able to find a water proof expoxy resin that already has the required environmental approval.
You would also not have to wait for a drought, you'd just have to unscrew and remove the boards currently under water, and replace them with refinished boards. You'd have to start with a few new boards to rotate into place while the wet ones dried pior to being refinished, but the additional expense would be minor and it would keep all the steps in service other than for an hour or so while swapping boards.
