There are races that have different categories of "Athena". I haven't seen it in a tri, granted, but I have in a marathon. Portland Marathon actually has Athena groups by weight and they weigh you at the expo. It's a bit humiliating but it keeps things honest.

A lighter person will generally do better than a heavier one. Look at the elites, they have almost no body fat. I think Athena shouldn't be a substitution for out of shape but I see it as a "normal" category as opposed to the really really good people. I did do a tri once where I saw an awful lot of "professional Athena" looking sorts...and they did expect to win.

I'd say if you can race Athena, go for it. If you're over that 150 lbs, you're at a deficit. I wish there was another category, like ultra-Athena? Something...because I can also relate to those people who have never done a tri or who are substantially heavier. I know how intimidating it is to be new and feel awkward and feel out of place.

I know that I will race Athena when the option is there. It's not like I want to take an award away from someone else but I also know that I will never see an age group award for my age group unless I'm 80 and improve a LOT