I would have to say that if you are working at 60ft then it has to be modular, unless it's just a few windows. Windows at that level normally come in large banks and when on a pole for 20+ mins at a time you need the most rigid and lightest available. It has to be said that modulars are tricky to erect and there is always a chance of leaving or stepping on a section, however this is outweighed by the extra work you can do with the pole due to not feeling as creamed.
Simon.