>>the reviews I read seemed to indicate that the GR60's actually are an improvement over the Studio 60's.<<
I read one review like that, but I do not agree. The GR 60's are nice speakers, but not in the same class as the Studio 60's. Monitor Audio did offer a package upgrade so you could put the GR60 drivers into the Studio 60. Interesting idea, but I would be reluctant to do that. The GR 60's have a different sound, do not image as well, do not have the top and bottom extension, the silky highs, do not completely disappear like the Studio 60's and the Studio 60's are more coherent. This is based on my ears and my taste, but I have e-mailed with several other Studio 60 owners who feel the same way I do.
The Studio 60's retailed for $12,000.
GR 60's retail for about $4,000.
IMO, there is no comparison between these speakers.
They are different entities.
Finally, this may or may not tell you something, but iit must be pointed out:
Every day on A'Gon, you will find two or three pairs of used GR 60's for sale.
I have been watching A'Gon for years and years and have never seen a pair
of used Studio 60's for sale.
Tells me two things --- a lot of people buy GR 60's.
No one ever sells a pair of Studio 60's.
This is not to degrade GR 60's. They are competitive with anything In their price niche and anyone shopping in that price range should put them on their list of speakers to audition.
Studio 60's should be compared to much more expenive speakers, which is what I did before I bought them.