Absolutely cater this. It's worth it. Maybe $700 for the food? If you pick it up and just put it on small burners outside, it can be picnic style and the whole thing stays warm! And cheaper than having them come to your house and set it up. It's a nightmare, no matter how big your house, to keep food rolling and keep it warm. And cold burgers are the worst!.
We do catering BBQ from Rocklands in Woodley Park. It's SO SO yummy.
Absolutely do this.
I've done the cook-by-yourself-for-party-for-70 thing. I like that kind of masochism. But it is a full-time, all-day, 15-hour gig. You won't talk to your guests, you will spend the entire party, and the entire time before and afterward, serving, cleaning, and managing logistics.
If you want to talk to the guests, get it catered. That's just too many people to do otherwise.
BTW I like BBQ. I think everyone does. (Except vegetarians/vegans. Order them a pan of bean and/or veggie enchiladas. And make sure some of your sides are vegan. Coleslaw with vegan mayonaise is pretty easy and available.)