We've been down this path several times over the past year. See these threads:
USTA Restructuring leagues in 2013
2013 League Restucturing (sic)
New USTA changes (whats your season looking like)
We've yet to start 40+ in our area...since they've made the crazy decision to play it in July and August (in the same months and day/time slots as Combo). While I think some of my (age) peers may have warmed to playing in it, it remains to be seen how many teams can reliably field two singles lines in the heat of summer or how many facilities can block off adequate courts for the increased match lines.
I am still going to sit it out.