Depends on how much it means to you to run with these guys.

I guess I am going to be in the minority here, but if it were me I wouldn't go back. Why?

I don't care.
I don't need to push myself that bad to be able to ride that fast.

I'd prefer a REAL 18-20 ave. ride, and I would try to find people to ride with who feel the same way.

Again, this obsession with speed...this group ride testoserone-fest....not for me.
Now, if you have aspirations of racing and high-level training and you WANT to go 27 miles an hour, then go back and take a beating. That's a great way to push yourself to get faster and keep track of your progress by seeing how long you can hang with them.

I guess I think it all depends on what a rider personally is looking for out of his/her cycling.