Ahh I totally forgot about this thread.
But today I actually did the test, testing the same sample at 2 different speeds/sizes.
I have a drumloop sample which is 262144 samples long. I loaded it into a table and play it back as usual, at the original speed.
And then I took the SAME exact sample and changed the speed of it in Audacity, so it's 131072 samples long, so its double speed/pitch of the original so it only takes half the table space. Then i loaded it into a table and pitched it one octave down, so both loops are played back at the same speed.
The result I am hearing is that the sample that is 2 x speed and pitched down sounds seems to be more muffled/rounded. It seems to be a little bit lower in volume and it also seems like some of the high frequencies are cut.
I think it actually does not sound bad, as it cuts out some of the highs for the drums. Personally I can work with it and I think actually especially on drum sounds it can make it sound better, give it a bit of 8 bit sound
I then got curious about making one version that was 4 X speed. That did not sound too nice, very muffled and too rounded. Again tested it on some drums. It might work better on other types of sounds, who know.
So the 2 x speed is definitely something I am going to explore more in the future. If I can get double out of the sd-ram by for example having alle drums samples running at double speed and pitching them down I a going to do that.