Jorge hasn't responded yet, but I can address a few density issues with pt/pd. The maximim density that I have seen in a traditional pt/pd print is around 1.5 to 1.55 or so. This involves double coating the paper, and using paper that inherently has a good synergy with pt/pd.
If you single coat the paper, you will max out in the 1.35 to 1.4 range on the same paper. The difference is not great, but the difference in the visual impact is very substantial, especially when you compare them side-by-side.
If you pretreat the paper with oxalic acid it may inprove the depth of the blacks a little. You can also put some PVA in the coating, which will help it resist absorption into the paper. That does improve the blacks a bit, but it is easy to overdo it, and the tonality of the print suffers.
If you use a rod to coat, it is possible to actually not put enough material down on the paper. This will result in anemic density normally. Using brushes will normally not result in too little material, but it is possible to get too much, so that you get wash-off in the developer and clearing baths. This will also reduce density, but it will basically kill the print anywhay, so a print with wash-off is not generally going to ever be shown to others as a suitable print.
If the Moon is in the seventh house, and Jupiter aligned with Mars, all these variables become moot, as every print you do at that time will be perfect and, alas, the results will be unrepeatable the next time.
The other issue is printing style. Some people print in a high-key manner, and others in a more straightforword way. Some people even print on pt/pd in a low-key manner. While these people may not be really getting syubstantially different performance out of the process, the results are radically different due to the way they place tones on the print.
A good example of a high-key printer is Keith Schreiber, a more straight printer would be Dick Arentz, and a low key printer would be Fluor Gardunio. It's hard to appreciate the differences in these printers without seeing actual prints, but I can assure you, thay all are operating within the laws of physics, and the confines of pt/pd printing!