As far as I understand it, the Rohloff is basically a seven-speed hub with an "underdrive" that reduces all seven of the topmost gears to give an identically (in percentage terms) spaced range of much lower gears.
As you say that gears 8,9,10 are respectively the reciprocals of gears 12,13,14, the "seven-speed" is almost certainly a simple one like the old SRAM Spectro 7 rather than a more complicated arrangement like the Shimano Nexus 7.
Correction to the above phrase in italics: the Rohloff isn't a simple seven-speed with 3 epicyclic sets like the Spectro 7, it has 4 epicyclic sets in the first stage.
I did once have enough curiosity to count the teeth on the sun and planet gears (and the gear ring) during disassembly of a Sturmey Archer S5/2, but have since forgotten.
As far as taking hub gears to bits is concerned:
- Sturmey Archer and SRAM three-speeds are easy to completely dismantle. Sturmey Archer S5/2 is a little more complicated as it is necessary to take the timing into account on reassembly, but still relatively straightforward. I strip these hubs down every few years to thoroughly clean out the old oil and check that the internal parts are undamaged. Until recently (not sure if this is still true), it was possible to get any necessary spare part for a Sturmey Archer three or five speed hub relatively cheaply, not that I needed to very often.
- SRAM Spectro 7 doesn't come completely apart like a Sturmey Archer S5/2, for example the planet cage and planets are a modular unit, but is still relatively easy to strip down, clean, lubricate and reassemble so long as you don't try to dismantle the bits that aren't supposed to be taken apart.
- Shimano Nexus 7 and Nexus/Alfine 8 are more complicated, so on these I haven't yet tried to do anything more than removing the internal from the shell and wiping it clean, lubricating it, then reassembling it into the shell. I might have a try one day if/when I break one, but if that happens, given the prices of Shimano spare parts it probably won't be worth repairing, cheaper to replace the entire hub, or at least the internal.
- With Rohloff, I reckon the idea is that it is supposed to be reliable enough never to require being taken to bits by a home mechanic, and too complicated to be done without the factory tools if by bad luck it does break. So I am not curious enough to try and take one to bits to count the teeth on the internal parts.
