I'm working on this movement and am generally having a blast. I am however a little hesitant since I hear the main allegro inquieto tempo rather slower than the norm. Horowitz's tempo (judging from the web clip I've heard) is around the 126-132 dotted quarter mark. Gould's video recording is about the same, about 120-126 per dotted quarter. To be honest I didn't "get" the first movement until I listened to the Gould video recording (different from his later studio recording, which is a little faster), which is on youtube:

http://youtube.com/watch?v=D8DtwYJSJdw

However, many pianists take this movement much quicker. Freddy Kempf takes it at around 160, and Pollini is even faster at 168. One of Richter's recordings is slightly slower at 152 (haven't sampled other Richter recordings, and yes I'm aware he premiered the work). But I simply don't hear it this quickly. I really hear this movement in the Horowitz/Gould I tempo zone, but I fear that if I play it this way in public the audience will think it too slow and not exciting enough. I would counter that a slower allegro inquieto emphasizes the march-like aspects of the movement, and would allow the climaxes in the development to truly ring powerfully without the need to slow down the tempo when the textures get thick (which is what faster readings tend to do).
So, do you think I'm a coward for wanting to take this movement at Horowitz/Gould I tempi?

P.S.: I've heard that Prokofiev himself approved of Horowitz's recording, though I was unable to get an exact quote on this matter. Anyone care to help me out on this, since I do not have access to a good music library?

There's nothing "cowardly" about it. Take it at a tempo that works and is reasonable for you. I don't like it at Pollini's tempo. For my tastes, I find that it sacrifices clarity in both the harmony (as it applies to Prokofiev) and in articulation. Any faster than 138 is too fast, IMO. Sadly, Prokofiev Bartok and Stravinsky share the same stigma amongst pianists that anything marked allegro has to be as loud and as fast as possible. The character of the music should determine the tempo.

Horowitz sent Prokofiev a copy of his recording of the piece. Prokofiev sent Horowitz a copy of the score with the inscription, "For the miraculous pianist from the composer."

I agree with Brendan that you should follow your own instincts, rather than catering to audience expectations. I also agree with the slower tempo. Without wanting to get into an actual program or plot, there are definitely militaristic and marchlike aspects to this "war" sonata.

Many thanks for your assurances Brendan and Hank. I agree wholeheartedly that details in articulation go by the wayside when taken too fast (so much of the first movement sounds like a blur in Pollini's recording). Usually I don't think too much about audience expectations, but with such a famous warhorse it's hard for me not to, especially since this will be my biggest warhorse so far.