Speaker upgrade recommendations pleae.

For a very revealing speaker that is also very neutral I would look at Silverline Sonata II's or their monitor the SR17 (but you would need a sub) and for a very detailed speaker with a very smooth and natural high end I would look at Tyler Acoustics Linbrook monitors (I'm currently breaking in a pair of the Linbrook Signature Systems and I am very impressed - they are much easier to set up than my main speakers but a bit over your budget). You might do some research on both of these manufacturers products.

What I mean by I love the SF sound is the Concertino's are SF's entry level speaker and I am ready to improve my system. My budget would be $2500 and I would rather purchase used from a good Adiogon member.

You love the SF sound but you are looking around? Pitty your wife. :-)

What exactly are you looking to improve in getting new speakers? Tonal differences - more bass - more dynamics = better imaging, etc? Oh, and whats your budget?

The Puccini is a very synergistic match with Merlin TSM monitors. In fact, I recently helped a friend put together a nice sounding system around that pairing. We were trying to find a nice match for the TSM, and BobbyP, of Merlin fame, recommended the Puccini SE as a top choice in the price range we were working with.
Mated with a Bel Canto DAC2, Pioneer DVD as transport, and a bunch of Signal Cable, my buddy has a great sounding, elegant system on a modest budget. Cheers,
Spencer