I think you have to decide what you want as a finished item George. If you want the most accurate scale representation of the real thing then you should paint the handrails. If you want the model to be a display of the model maker’s art and show a degree of the work that has gone into creating it, then leaving the handrails bare brass is also an option. I have seen a tug model in the past that was plank on frame construction and the entire tug was simply varnished, not a drop of paint on it. Not an accurate scale model but nevertheless a beautiful display.
Remember though that bare brass will tarnish with age and pond water so you either need to varnish them or frequently polish them.
I actually think there is also a degree of not wanting to cover something up that you are, quite rightly, very proud of. I remember the same feelings when I finished the handrails above. My aim though is always the best scale representation of the real thing that I can create so, inevitably I go for painting them and then adding a light weathering wash as well.
The final consideration was pointed out by Colin above, handrails on tugs were never brass so to some people brass handrails on a model tug looks a little odd.
One thing I would suggest, for something that is going to be such a significant aspect of the model, is to stop and take a breather. Don’t rush into anything. You have to be totally sure in your mind that whatever you decide is what you want and you are not going to regret it in years to come. Maybe even make up a small sample length of railings and paint them so you can compare the two together side by side.
Waffle any day you want, we do!