Hello and thank you for your enquiry.
Yes the Heavyweight is indeed likely to last longer, because it is made in a thicker, tougher material.
I’ve put together a little table so you can compare them:
420D PU-coated nylon (PVC-free. Stays supple in sub-zero temperatures).
500D polyester-reinforced PVC tarpaulin.
Removable shoulder straps.
Multiple attachment points for straps or lashing.
Internal ID pocket.
I hope this helps. Don’t hesitate to ask if you have any other questions.
Thank you for your interest in Aquapac, we appreciate it!