Imformation on Grafting Tomatoes?

I was looking on grafting some yellow pear tomatoes with some Roma's and was wondering how that works. Does it produce a fruit that has a blended flavor or does it just have lets say yellow pear roots and roma tomatoes? I was going to graft them when they are about 3-4 inches tall so that might help. I also was going to cut off the stock of one and graft it with the scion of another. Thanks!