Just to be clear, the main reason I used 55 was for the high quality negative. If I need a decent positive 4X5 print only, then I recommend Fuji FP-100B45. This material is very good, sharp and consistent. We are not trying to make a print material - we probably will have a print, but its purpose will be to accomplish the reaction necessary in the DTR process to produce the highest quality negative - such as we came to know in 55. That means no "sideways" diffusion, and we need fast, direct solution of silver salts over to the receiver (print) to do that. Then the kinetics of the process chemistry will have an effect on the characteristics of the negative. That's very important. I never understood why some people thought of 55 as a positive print producing material and threw away the negative when there were so many other black and white print materials available, but of course the user gets to choose how they use the material, not the manufacturer.
Polaroid developed type 55 under the guidance of Ansel Adams and, using what may have been a Kodak Aero product or something like Panatomic X, managed to produce a quick and sharp negative with little grain clumping, and fine detail using only a single a reagent, close to certain monobath formulations, but that are unlike most of the other Polaroid B&W reagents.
The negative is the focus of our attention - a negative so good, so convenient, and accessible to all, that we can afford to travel far from Jobo tanks, or dip-and-dunk, or other inconveniences, and still enjoy the process of fine image making, with its magic and technique, sans batteries and USB cables.
We can certainly make a positive too, but that's not where the need is. Like composing on an upside-down ground glass, examining a negative becomes second nature with a little practice, and with 55, or maybe New55, you might do it within a minute of exposure and still have light for another shot or two. Scanners have become so good and cost less than a kilobuck or less. Yet truly high resolution on-camera digital capture devices, such as those made by Phase One, are still up to $45,000 to buy, and too far out of reach of all but the most affluent, or urgent.
So with simple and inexpensive tools such as an old Speed Graphic, a 545, and some field processable material, the artist, the newbie, the student and the old pro can still produce even higher quality images, without a darkroom, and still have money left over to buy a new car!