I have gigged TOTL Rolands for over ten years now. Five to ten gigs a week, 4 to 8 hrs a day, during the season (March to October). Usually outdoors, often next to the Gulf of Mexico on the beach... Basically, close to the worst environment you can be in.
NOT ONE PROBLEM..... EVER.
Mind you, I NEVER let it sit in direct sunlight, and use a full ATA flight case for transportation. But, all in all, my experience is that build quality does make a difference if you play a lot in hostile environments (other than Baghdad)...
(Disclaimer... SOME others may not have had this good fortune, your mileage may vary, objects in mirror closer than they appear, it's just what happened to me...)
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An arranger is just a tool. What matters is what you build with it..!