It is too bad that mainstream classical audiences (if that phrase isn't an oxymoron) are still basically unaware of or uninterested in historically informed performance, especially for something like solo keyboard. Of the hundreds of recordings of the Goldberg Variations that Eisenberg mentions are available, a number are harpsichord performances released by specialty/audiophile labels. A few examples include Frisch on Alpha, Vinikour on Delos, and Hantai on Mirare.

Admittedly I'm a HIP purist (you couldn't pay me to listen to Bach -- or Scarlatti, or for that matter Mozart -- on a modern concert grand piano), but I really do believe that hearing this music on the instruments for which it was composed (harpsichord, lautenwerke, clavichord, fortepiano, etc.) can be a revelation for anyone willing to hear this music on its own terms. We are so used to imposing the sonic and musical idioms of the 20th century on early music (pre-19th century, with Beethoven as a contentious transition) that this can be difficult at first, but after the initial shock wears off, you'll never go back. Thankfully we live in a time when performers, instruments, recording techniques, record labels, and early music societies make historically informed performances of superior quality both accessible to everyone and worth accessing even to non-purists.

They sort of suck, generally. Kind of tinny-sounding. I'm thinking of late Beethoven sonatas played on a fortepiano of Beethoven's day and recorded by Astree. No, I'd rather have a regular Steinway Grand doing these works--or Mozart piano concertos, for that matter. Same for late Haydn. The dynamics come through better.

However, you are right about Baroque keyboard music sounding better on a good harpsichord than on a piano, particularly with composers who utilized the characteristic attack of the plucked strings, such as D. Scarlatti and F. Couperin. This music loses when played on piano. The same is probably also true of the Handel and Rameau suites. Bach, I think, is universal enough to come through on any instrument (even Moog synthesizer), though given the choice between the WTC and Goldbergs played on a good harpsichord or on Glenn Gould's piano, I'd choose the good harpsichord. (I'd choose GG's piano over a bad harpsichord, unless it had Wanda Landowska playing it).

When it comes to string instruments, I think it's also a mixed bag: I've heard good versions of Bach's solo suites and Partitas done on period violins, and I've heard bad ones. Gamba music sounds better on Gamba than Cello. But the performer counts as much as the instrument.

genedio:

They sort of suck, generally. Kind of tinny-sounding. I'm thinking of late Beethoven sonatas played on a fortepiano of Beethoven's day and recorded by Astree. No, I'd rather have a regular Steinway Grand doing these works--or Mozart piano concertos, for that matter. Same for late Haydn. The dynamics come through better.

I've not heard any fortepiano recordings on Astree, so I can't comment on those specifically. I wouldn't try to insist on fortepiano for Beethoven, especially late Beethoven, but I can say that Ronald Brautigam's series (sonatas 1-20 so far) on fortepiano for BIS is rendering all my other Beethoven recordings unnecessary and decidedly inferior as it progresses.

Your comment about the dynamics coming through better on a grand piano begs the question against the HIPster. The claim is that "the dynamics," i.e. those that are actually in the composition, are what can be produced by an (ideal) example of the instrument with and for which the music was composed. Even if the composer wished that the instruments of his day had a greater dynamic range (or some other feature that the didn't have), the fact is that he composed the music with and for the instruments that there were. What you mean is that you like it better that way.

At any rate, if one listens to good fortepianos (or tangent piano) well played and well recorded (by people such as Brautigam, Staier, Spanyi, and Egarr and on labels such as Harmonia Mundi and BIS) I think that no one without a prior commitment will be able to insist that a fortepiano is just "almost a real piano." These can be wonderful instruments in their own right that, by the way, allow for many kinds of subtle and explosive dynamic expression impossible on their giant descendants.

Axon:

...good fortepianos (or tangent piano) well played and well recorded (by people such as...

Also Levin on Archiv and L'oiseau-Lyre.

and well-regarded at the time. Perhaps they were the first fortepiano versions. I haven't heard the Brautigam versions of Beethoven's sonatas 1-20. I think Beethoven is obviously a special case, though Clementi and late Haydn (Sonata in Eb #62, Piano Variations in f) would also seem to benefit from the wider dynamics obtainable on a modern grand. I believe these dynamics were written into the music, and are not spurious accretions of the performers. Mozart piano sonatas are generally less dynamic than the Beethoven Pathetique and most of his subsequent sonatas, and the larger works of Clementi and Haydn. The bottom line still seems to me the performer, and there is a much wider range to choose from on grand piano vs. fortepiano. But perhaps this will change. I am certainly not arguing against newer renditions on period instruments; all I was saying is that in the case of Baroque keyboard works, the advantages are much clearer, and have also been recognized for quite some time.

With the organ, I am not so sure. I still prefer hearing Bach's larger pieces on substantial instruments with 32' stops, rather than period organs with 16' stops--but the difference is not quite as stark as between the fortepiano and the concert grand. Organs really have their own character with respect to the mix of various stops, reeds, etc. Some baroque organs are more than tolerable, as they have been retrofitted.

Another area where I prefer period instruments of the baroque hands down over their modern equivalents is in lute music, which sounds vastly better played on the lute than the guitar. Partly this is because of the recent crop of good lutenists, and one can get good renditions of Weiss, Gaultier, or Dowland today where a couple decades ago the pickings were slim, indeed.