And you paid $60 according to that site... Hoping you didn't jump to this forum for the sake of the advertizement... And if you didn't - welcome to the forum.
Yes, you should expect higher yields from the grafted plants, and yes, you should expect higher disease tolerance/resistance, that is the purpose of the grafted heirloom quality plants to the strong, vigorous root stock, be it Maxifort, Emperador, Colosus (just to name a few that available to home growers as seeds). These F1 hybrids were purposely developed for the reasons I've mentioned above.
But paying $20 per plant is... If anything, Territorial Seeds have far better pricing and indeed the selection of grafted varieties, at $6.75 per plant [url=https://www.territorialseed.com/category/s?keyword=grafted]www.territorialseed.com[/url]
Usually, if someone has very limited space, or fusarium and or verticulum wilt issues in their soil, this would be a good option to get a good crop. Last year I grafted Kosovo to Emperador root stock, and intentionally planted it to a place where I know fusarium lives in my property. Not a single sign of it ever showed up on the plant, and I kept vine to only 4 main branches. Very high vigor, great tomatoes, exceptional resistance , thanks to that root stock. I'm sure it's going to be no different this year...
Good luck with your grated plants!