Well, I agree, but since Kontact alluded to thinking about what it actually might take to make them work and to think about if the wheel swap is really just a swap:

the way a Sturmey AW hub fits a frame, they don't all fit the same.
Are the 29er wheels for derailleur gearing? Any issues there if you swap in the wheels from a Raleigh 3-speed?
The front wheels should be no problem, except the fork end spacing might not be a match,
the brake shoes might not match up to the smaller radius 26" wheels.
In the back if you don't transfer the trigger shifter to the 29er you won't have any 3 speed shifting.
If you don't get a narrow-width Sturmey sprocket the narrow MTB chain might not run smooth.
Will teh rear chainline of the Sturmey hub line up with the MTB front sprocket? If not you might have the chain throwing.
Will the unused rear derailleur be somehow in the way?
Finally, will the brake shoes line up with the rear wheel?

This could easily turn into a lot more than just a swap.