Comet indeed seems to be really powerful. I did something similar, where I used a bunch of Comet towers and built a Deceit tower for every 4 of them. It was extremely lagtastic, but worked surprisingly well for a tower that does not deal damage in an area. I've been having fun with all dual towers, as in going only for one specific dual tower (and adding single element tower if that tower was a support type like Deceit), and as soon as I went for Comet, I easily doubled my record of fruit kills. Also, normally, I had trouble with waves that resisted my dual tower, but with Comet, the only time I leaked was once at the beginning because I did not have any triple tower set-up yet, and 12 lives at wave 59, because they were earth, but also because I was so focused on getting my towers ready for wave 61 that I did not upgrade my defense at all for a long while.
So yeah, seeing how you were at Very Easy, managed to fill up the map without Deceit towers, and increased their attack speed with another tower, it does not impress me that it's able to score infinite fruit kills.