If you're flying LA/LP/4M a lot, then it could make sense. Remember that AA credits LA (and the affiliated carriers) at 100% as long as they are cross-border legs:

LAN credit table for AA miles

If you're going to fly LAN enough to get at least mid-tier, then the LAN program appears a lot better for free upgrades. Their lowest tier gets upgrade coupons and their highest tier gets what appears to be unlimited upgrades on all flights. If my business took me south instead of east, I'd take a much closer look at their program.

One other note -- if you have sapphire/emerald with a non-AA airline, then you'd also get Admiral's Club access even when on domestic itineraries.

When I signed up for LANPASS, I never had any problems though I've had other minor issues with their website since. I still credit everything to AA at the moment.