Just to follow up, I went for 4x 1961 Monitor (the twin bass driver version) to go in as surrounds in a small Atmos room I'm putting together. Bottom line, I'm very happy.
They sound great and feel more premium than I expected at this price point. Cabinet finish looks better in the flesh and the binding posts are nice enough. Even the packaging (shipping) quality is a step up from what I thought it would be, which always gives you a bit of confidence, however misplaced that can be sometimes. And I had good & fast email communication with Arendal throughout. So, well done Arendal.
Anyway, just to start getting a feel for the room's issues, I'd previously thrown up an old pair of Dynaudio M20s in. But, for a laugh this afternoon I thought I'd finally get the 1961s out of their boxes and do a rough and ready in-room A/B measurement of one of them vs the M20. I used the left back surround position as an M20 was still on the bracket, and it's potentially the most troublesome placement since it fires at a computer screen and desk, and is in a corner. For what little it's worth to anyone else, here's the graph:
Orange = Emit M20, Green = 1961 Monitor. No EQ @ 1.5 - 2m. 1/12 smoothing.
Obviously there's the usual mess on the left of this. i.e room issues, SBIR etc... (Might have to see if I can fix a bit more of that...) But anyway, to the right of all that, the 1961 is looking pretty healthy! Another thing to note, that traces are absolute, so sensitivity is very comparable to the Dynaudio. (Not that that's a great reference point, but, I was expecting these to need more power for some reason.)
Just playing with some EQ by ear, it feels like they'll respond well to pretty much anything I need to do. They are *maybe* coming in a hair bright for my liking, but difficult to judge as the subs haven't arrived yet and the room's not really finished.
I'm pleased to say the most remarkable thing about them is the headroom; which is why I thought I'd try them in the first place. They're definitely the most SPL capable speaker of this size I've ever tried - but then they do only go down to around 70Hz, so...! (Most SPL capable while still delivering relative hi-fi, I mean.)
While they're specifically intended to be used with a sub, if you wanted a desktop/nearfield speaker for lower level listening, I reckon you could shelf LF up quite a bit as the speaker rolls off and have something very, very listenable even without sub extension. Within reason of course. I tried pushing a ton of EQ in to them at LF and, at moderate level, they were sounding excellent! Then I did find the limits, and thought I'd better calm down both the positive EQ and level before anything bad happened...