One of the reasons why I prefer Marine Band Deluxe and Crossover is that the sandwich construction and small number of reed plate screws makes them the easiest harps in the world to work on. When tuning or offsetting reeds (something most players rarely need to consider), these models lie flat on the working surface once you’ve removed the covers and the reeds can be accessed and filed without difficulty. The recessed reed plates and projecting mouthpiece of the Special 20 mean there’s a considerable risk of the file scratching the outer edges of the mouthpiece when working on the reeds if you do this without completely disassembling the harp first. As I’m lazy and have to perform this task fairly often, I prefer a model which I’m less likely to damage 
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