Seriously....try before you buy! It's like buying shoes, based on a recommendation!
I've never fired a Benelli extensively ( a few shots, yes) and my kid's 870, I've used some. Neither fit me to my preference, but both worked. However, I've been doing the shottie thing enough that I can compensate a bit for a poor, but not terrible, fit.
But if you're going to be shooting a lot (i.e. Trap) fit is
vital. Both for comfort, and effectiveness.
As for "cycle speed"....last year my 13-yo went 88/100 at Trap Doubles at the Mass State Shoot. He dropped a few of the first birds, too.....
If you're able to try them both, first, you'll be surer in your choice, and therefore more confident that you made the right one. That's
wicked important on the Trap line! The fewer rats in your brain, the better.