OAT membership

Good question. To be honest, I don't know how much of an incentive there is for joining. If you are an OAT member, you save $5 per event in terms of even registration cost. You need to participate in at least 8 events to break even as OAT costs are $40/year.

There are some retail benefits but really, they're no big deal and similar (or better) prices can be had simply by buying at the right time.

http://www.triathlonontario.com/hm/inside.php?id=204

If you're a member of an OAT sanctioned Tri club, your club membership already includes the OAT membership which then gets you the even registration discount.

The biggest OAT membership benefit is for the Tri clubs who get liability insurance once sanctioned by OAT. As for the generaly AG athlete, I'm not so sure.