Then there were 2

OK I have 3 amps on my short list but one is not available due to supply chain issues.They are ARC Ref75SE, Rogue Stereo 100, (and not available is Quicksilver Mono KT/120)
Question sin it is down to the Rogue and ARC are the comparable (or as they say a coin flip?) or is one considerably better than the other.
I like the fact that the ARC use KT150 and the bias is accessible on front panel.
I checked, I also saw no used quicksilvers, that tells you something!

My job designing corporate office space, projects typically 18 months start to finish: I told my employees part of their job was to keep me from compromising under pressure. It's always a war against the forces of compromise.

Not that ARC is a compromise as much as: In 3 years, what do you want to wake up and see/hear in your system?

I meant buy anything interesting used or new that you are confident you can re-sell when the Quicksilvers FINALLY arrive. 

For the difference in price too many options exist,

pounds is usually transformers, heavy oversized parts. two quicksilvers at 82 lbs or 1 ARC at 47 lbs?

Personally I like the look of the quicksilvers more, and, think thru the use and related costs of existing or new cables: the different lengths involved if monos or stereo.

it's a fun problem to have, best of luck deciding.
My reaction is exactly the same as @atmasphere . What are the speakers will you be pairing?
Do not underestimate the Rogue Stereo 100.  It is extremely "clean" with a low noise floor, very good detail and articulation.  Although it is a tube amp, it is not overly warm and is definitely not "diffuse".  I had one paired with Sonus Faber Amati tradition speakers and it was extremely good.  I traded it for the Rogue Apollo Dark Monos which are truly spectacular.  (Primary reason for trade was I felt I needed the extra power and wanted to make the next step in terms of articulation, lower still noise floor, etc.) Rogue is a quiet company. Mark Obrien is a genius in design and is nearly always available by phone to answer questions, discuss the components, etc. Fantastic support.
@craig I own an RP7 so I know how accessible Mark and Nick are. Very good company to deal with. I find their stuff a little to much like solid state, i am getting used to it. I did demo the QS and a VTL in my system and it was very good.

@elliot I am using my own 2 way speakers two MW16P and TW29R Satori drivers. Room is 14x22x7
Are you sure the M120 is not available? Did Mike tell you that?