Save on the cost of the treadmaster (it is rather expensive!) and apply a non skid surface (eg using seived sand, for uniform size of grains) with the final couple of coats of paint. Works brilliantly.
I agree with bajansailor, what can look really good is if you used 2inch wide masking tape to break the deck up into rectangles before you do the last couple of coats with the sand you get a really good contrast. Makes it look professional.
I tend to disagree with the advice above. I have a steel boat and also spent yonks on merchant vessels. Steel decks can get bl**dy hot in the summer and my boat is fitted with smooth nonslip panels, cooler to walk on and more comfortable on bare feet than the diamond pattern stuff.
What ever you do dont use treadmaster on steel decks,No matter how good you stick the stuff down you will eventually get rust under it and will have hell of a job to get it off.As suggested use a good deck paint,then you can see if you have a prob. later and deal with it fairly easily.In my opinion the same can be said for teak decks,wood and steel dont mix. Having had steel boats for over 25 years.
Whatever you do, treat the decks with a really good cold galvanising paint, not galvafroid, (unless thats all you can get) there are some even better ones available now. Which will really stop the rust for many years. We use one on the rig here and it's excellent. Can't get the name as yet.