Thoughts on B&K Ref 50

Not sure on how to title this thread, I'm after opinions of owners or anyone who has serviced them to give me some insight on what to expect long-term.

I have just recently acquired one and it appears to be in pristine condition, no issues, and I will lay my eyes on it in a couple days. Since the service department of Eastern Elite doesn't work on them anymore as of this month, I really don't know what I am getting into.

I have a B&K ST202 amp and I really like it, but don't have a dedicated preamp yet just using my AVR. Seems there were issues with clicks and pops and some stated this was with toslink but not sure of that.

I don't know of the firmware version yet but I also have been told to not mess with what works. If the unit works then a firmware upgrade could lockup the unit and I surely don't want that.

I hear too many good things of a B&K pre/amp combo and I definitely want to give it a try. If I removed the Ref 50 from the setup, would a Aragon Stage 1 be an equal trade or what would you recommend? I'm only asking this if I need to unload the Ref 50 but hopefully not.

There are threads on the Ref 50 but I'm after a more current debate, any criticism appreciated.