The NPS will do things in the print stream that the Docusp cannot.
You can automatically run batch programs to run conditional merging on NPS's, Docusp can only dream of that, i have tried to make it work.

So this "Fred Flintstone" probably has a good reason other than not getting pressured into buying something that won't work for him.

You have to buy the added licensing for the NPS compatibility.

The Docusp ignores alot of embedded PS that might be written by programs that are 8-10 years old, but were very expensive to buy, and still work great.
The analogy of stone wheels versus michelins isn't a good one.

The program i dealt with automatically took the conditional data, and merged it with conditional images that it sent over to the NPS through FTP, then took the data and images as it was printing. Docusp can't or won't interprete the intelligence in the PS datastream.
PDF isn't an answer, PPML might, but if PS2 for them, why reinvent the wheel, they probably just need a bump up to a higher version of NPS.

Customers aren't stupid, they know what they want, i have spent countless hours getting them what they want by listening to them, instead pissing them off by getting them into something they don't want by ignoring them when they need help.

And Dos was extremely stable, but i don't use it anymore because my applications can be transferred to newer OS's, It doesn't mean that Dos was bad.

(attached)

This is a free country.  If some guy wants to run DOS on his PC and use that to send files to his DT135  (or 4635) that is certainly his right.  I recently came across a printer who still does his invoices on a typewriter  -and not even a Selectric!  Different strokes for different folks.  The tires on the bus go round and round  -even if they are stone.