I was using flite 1.1 and I'm not sure how to check memory usage.

I tried it while the player was playing and no, it sounds just like DomoKun's date anouncement... so bad that you can't make out the speech. But pausing the player (without quitting), it plays just fine. I haven't tested any large files, just some short phrases. I'd like to see if I can re-compile flite and add a couple features (like upsampling and writing to stdout).

For a GPS app, it looks like it would have to pause the music, speak and unpause. I'm still interested in working towards my initial goal, but I haven't even started on IrDA (which AFAIK isn't in hijack kernels).