I'm running Catalina on my desktop and it's been good to me so far.  I am holding off a bit on the jump to big sur.  My plan is to wait a few
weeks justto be sure there are no dangers lurking.  Mainly because I run Parallels forVMs and even though they've said it's compatiable with Big Sur.... I'm nervous.
I would say if you use that iMac as a regular desktop machine and don't doanything too wonky there is not a reason to hold back.  Big Sur had
the longestbeta cycle of any recent MacOS release.... so I it's looking pretty solid.
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Ah ha; yes, I agree that since you're running parallels I'd hold off. :P You  know, I have one stand alone iMac Pro - so I guess I'm gonna go ahead and give  it an install. I've got nothing to lose, its really used for media consuption  these days so - I could go back to stock and not bat an eyelash. 
I'll report any crazy issues here, but bet that it'll go off without a hitch.  That article you posted was really helpful in knowing what I'm in for.
Really, I think this upgrade is about the polish and perfecting the ecosystem.  Big Sur feels like iOS or iOS feels like Big Sur - they just fit hand in hand  and look almost perfect, IMO. Much can be said about how awesome Linux is to  control your systems.. and it is. But anyone who says MacOS isn't beautiful,  strong and SOLID is... blind or just hates Apple.
It's really nice, it stays up, and you can give it to grandma. Isn't that what  [one kind of] great OS is supposed to be? 
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