Even the plastic guards do wonders for helping save your grips in a wreck, but the wrap-around kind are definately the best.
As for getting your hand caught, I have one question:
How many people here have, or know of someone, who has ever caught their hand in one of these? I never have, and just cant see getting caught in them. They have actually protected my hands several times when I went down.
Back to the original discussion: AL throttle tubes.
If you choose to use the AL tubes, I would suggest using a good dry-film lubricant between the tube and the handlebars. Metal-to-metal contact usually leads metal fretting and causing it to stick. The dry-film stuff also does not collect dust. BTW, they use molybdenum disulfide dry-film lube alot on aviation stuff. You might have a hard time finding it, but it works excellent.