APX100 developed in Rodinal 1+50 produces excellent results (sharpness, grey tones). The data sheet can be found at
http://www.agfa.com/photo/products/de/pdf/.../C-SW16-D16.pdf
Exposure of APX100 as ISO 160/23 and development for 17 minutes (tilt continuously for the first minute, then once every 30 seconds). If negatives with higher gradients are required for a mixed-light enlarger, the developer temperature should be increased to 22 degrees (this also applies to APX400). Extending the development time is of no benefit.
If a particularly fine grain is desired (with slightly reduced sharpness), the A49 is a good choice for APX100 and APX400. Beautiful portraits can be achieved, for example, with APX400 and A49.
Enjoy!
Best regards, Otto Beyer!