How much to spend to beat $1200 10yr old speakers?

Phasecorrect, i agree, i heard the hot rod kestrels a couple years ago hooked up to some cheaper (goldentube) equipment and they were pretty stunning- so transparent, holographic imaging and good clean bass response- i wonder how the new Kestrel II will be, but thats a whole other price range- the imaging from the swift's was pretty holographic but they may be a bit lean as you said- at the time i thought maybe it was the amp- also, they sit kind of low for my ears, making images a little short- but hey, less than $1000 new- i'm intrigued by the quads but i think they'll be hard to find here in oregon

I very much doubt that speaker technology has improved to where a $600 new speaker would even come close to a $1200 10 yr old speaker. Perhaps a $1200 new speaker would improve ... which is not bad considering inflation.
I think you'd have to try, but I'd be very surprised if you sell the KEFs.
If you wish for more bass then I saw someone else suggested a separate powered sub ... it's worth considering ... I added one to my 10yr old spica angelus and it made an immense improvement. I think I'll still have the Spicas in another 10 yrs now I have the sub.

For those on the west coast...I believe Gene Rubin carries the new Quad line...also...the Maggie qr12s...the ones just below the 1.6s...are a great speaker...and roughly 1200 usd...if you have the room...a must audition....

All things being equal...a ten yr old $1200 speaker should at least equal a newer $600 one...but I wouldnt get too caught up in price ...there are simply not that many good speakers in either price range...and both the $600 Paradigm Studio 20 and the Quad 11L outperform a number of more pricey monitors(both old and new)....a higher pricetag can be just that...I value performance over price

If u like meadowlark kestrals.....try the Vandersteen 1c...virtually identical phase correct sound...for around $800....