The cutover point for the chain or u-lock decision is if you are skinny enough for the chain to be locked around your waist. If you can't wear it as a belt, then chains are a hassle to carry.

The NY2000 is lighter than the Fahgettaboudit Mini, but is much bigger, which gives you more locking options and is only marginally less secure. If the thugs have the gear to get through a NY2000, then the Fahgettaboudit or the M18 is not that much of a leap.

The Fahgettaboudit looks like it would give you the best peace of mind money can buy though.