That is a nice looking building, I like it! Conventional stud construction does have a lot of benefit when it comes time to do interior finish. Here is another method I recently used which gives the benefits during interior finishing. Pole construction, with bookshelf girts. With this method, the girts that are usually 2x4 added onto the outside surface of the poles, are instead 2X6 elements, laid horizontal, installed between the poles. So the girts are flush to the outside and inside surfaces. By doing this, they are avialable for screwing the steel siding to the outside, and then later available flush with the inside wall surface to attach wall sheeting to. Other pole building methods require a whole bunch of extra lumber to be added to the inside surface to mount wall sheeting. If placed on the usual 24" vertical center to center distance (as recommended by the vertical steel siding manufacturers, the resulting space is perfect for an off-the shelf fiberglass batt (a batt made for between trusses in the typical attic). When you wait for a sale, these batts are as cheap as insulation gets. Installation of them is really easy: cut to length, pop them in, they stay there.
Of course you would use all the usual methods with this such as: Tyvek exterior, poly layer inside the figerglass and under the wall sheeting. Here are a couple pics...
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