I agree, it is a very interesting subject.
1. If you use gearing, you have to worry about backlash.
2. Microstepping, as Mr RB states will not necessarily give much greater accuracy, it depends very much on the motor e.g. the stp97-5.pdf. What it does provide is smoother motion, and a way to get around motor resonance problems, and associated torque issues.
3. Microstepping doesn't reduce the torque to 10%, that's only in 1 of the windings, the other should be around 90%. The Allegro chips maintain close to constant torque through all the steps.
4. Ran across the A3955, it's in a 16pin DIP (but only 1 full bridge), so is easier for prototyping purposes.
5. Recon the A3984 looks good. Put a heatsink on it though.