The benefits of me putting together a group for OD next year include pre-sale even ahead of STH presale, getting to sit together, no service charges of up to $7/ticket, and a slight discount on prices.
It's a no-brainer for my group next year if there's enough interest. And since I end up having to buy a bunch of tickets for my ticket partners anyway (I bought 20 this year), it's actually less of a hassle then trying buying them during the STH pre-sale.
That's why I went that way the last two years, next year I won't do it again. I can get the same price using my STH card at the box office and sit a few rows back with a lot less hassle.