[racket] preference: 32-bit or 64-bit racket?

For the last four months, I've been using the 64-bit Racket on my spiffy new 64-bit Macs, and I'm now starting to wonder whether that's really the best choice. If I understand correctly, the memory footprint is likely to be substantially larger, and the payoff is--presumably--a speedup on certain kinds of program.  Those that frequently use ints that can be represented in 64 (or 63) bits but not in 31? Those that use doubles heavily? I suppose string processing could be faster, since (IIRC) we use 64 bits per character?

In any case, I thought I'd just ask: how many of you are using 64-bit builds, and how many are using 32-bit builds? Are there compelling advantages to the 64-bit build that aren't occurring to me?

John

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