Hmmm? The only other thing I can suggest is you read up on 'bedding the clutch.'
Chatter when clutch pedal is down sounds like throwout bearing to me...and I'm not sure how long it could rattle, but I'd suspect a long time.
Me? I'd probably monitor it closely, try bedding, and hope for the best while being prepared for the worst. I'm not a mechanic, so just know what I know...mostly...from reading here and paying attention in my buddy's shop.
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Mangofy your E46!