This has interest from a "could I drop in sax B if sax A fails without having to re-record the whole track" viewpoint. For me, anyway.
Are they alike (enough)?
Not sure. The "base-tone" is similar, but when pushed the Grafton has a point and slight aggressiveness that I think might be hard to get the Buescher to (with the current setup).
It's a real-world experiment more than a "shoot-out" type of experiment in that you play a musical solo rather than playing the same thing in the same way on both horns. Often, you get to a point in the solo that is natural to "give it one son", and this is usually on the Grafton, rather than the Buescher - maybe that was intended as you know the nature of the instruments?
The whole recording chain is a factor in them sounding as they do though, and my feeling is that it has brought them (artificially) closer together than otherwise, so:
Mouthpiece, reed, mic, preamp - to my ears they all lead to a less-detailed sound and more of a warm, valvey sound - again bringing the two closer together.
In the studio, this is a good thing! Interchangeable horns, mics etc can be an occasional godsend when there's no workaround to a drop-in.
In scientific terms, it's a flawed question - but, that might not have been your intention anyway (being scientific)..
Nice solo.