I neglected to mention that Gardiner's set of Beethoven synphonies also uses period instruments, but I believe the smaller orchestra is even more crucial to interpreting the music as intended. Beethoven was very specific about the number of instruments and the tempi, actually indicating the metronome markings, not just general "allegro," "andante," "presto," etc. Perhaps Hogwood also uses the specified number of instruments per section.
A friend of mine who is partial to von Karajan's recordings didn't appreciate the Gardiner version. His comment was, "The tempi are so fast." I was puzzled, because they didn't seem too fast to me. Then I listened to the von Karajan; I felt the tempi were sluggish. So, I checked the timing. Turns out that the Gardiner tempi are usually slower! (Gardiner was also very attentive to the tempi specified by Beethoven.) The smaller orchestra is more nimble, more articulate, and much more energetic. That energy seems to create the impression of greater speed.
The beauty of music, however, is in the interpretation AND the infinite possibilities of interpretation.
A friend of mine who is partial to von Karajan's recordings didn't appreciate the Gardiner version. His comment was, "The tempi are so fast." I was puzzled, because they didn't seem too fast to me. Then I listened to the von Karajan; I felt the tempi were sluggish. So, I checked the timing. Turns out that the Gardiner tempi are usually slower! (Gardiner was also very attentive to the tempi specified by Beethoven.) The smaller orchestra is more nimble, more articulate, and much more energetic. That energy seems to create the impression of greater speed.
The beauty of music, however, is in the interpretation AND the infinite possibilities of interpretation.