How do you decide whether to sign up to race in the Masters Category or the Age Group Category when you are over 40?

I understand that the Masters Open is for "elite" participants.  But let's take Gail K for example.  This year she raced in Female Open at age 39.  So next year, will she race in Masters or stay in Open Female or go to the Age Groupers.  I've noticed that some of the age groupers have better times than some who placed in the Masters.  In the Greenville Tri, the top 2 finishers in my age group finished 3rd and 4th overall female.  What's up with that?  Why don't they race in Open Female or Masters Open Female?

Hardly any ladies compete in Master Open Female?  Is it not want to admit your age?  Thinking you are not "elite" enough?   There does seem to be more men who will compete in Masters Open Male.

My guess in the Set-up series, Gail will stay Open vs. Masters because the payout is higher and she has a good chance of winning the Open. A couple of the 40+ guys race as Open due to the payout. It's not much, but it covers the race entries.

I know women have funny issues about their ages and weight. I see females that can easily go Athena race as AG. I don't think being a master is that big am issue to hide your age. One of the faster MF (Master Females) is 51. If she went AG she would have a 52 on her calf instead of MF or MO which might mean one think  she could be as young as 40 assuming she was trying to hide her age.

Hardly any ladies compete in Master Open Female?  Is it not want to admit your age?  Thinking you are not "elite" enough?   There does seem to be more men who will compete in Masters Open Male.

If you are competitive, I would sign up as a Master Female but If you aren't, AG is still a better choice. I think part of the reason you saw slow times in the master females is because it is not a popular category and some of the people who come from a running background are used to deciding between elite and open categories end up placing when the elites don't show up.  There are more men in just about every category.

In the Greenville Tri, the top 2 finishers in my age group finished 3rd and 4th overall female.  What's up with that? Unless they were planning on doing 5 or more races in the series, there is no reason to sign up as a Masters.