"FAR 8.1104(e) is simply stating what clauses to use and doesn’t really categorize anything." Exactly. So if you use a "service" clause, you just broke the law. Again you have to ask yourself, what manual, guidebook, comic book, etc trumps the FAR? At some point your office just has to make a business decision and stick with it. Otherwise you can make yourself go nuts.
"FAR Part 1.602-2 Responsibilities states that contracting officers should be allowed wide latitude to exercise business judgment. I believe the determination that a lease with the overwhelming majority of the costs are equipment related could not reasonably be questioned if solicited and awarded as a supply requirement."