Check out this link.
http://www.hdtvprimer.com/ANTENNAS/comparing.html
Net Gain for UHF Only antennas. Antenna L shows real world gain figures for the 3023 aka the 4228. The 91XG is a very good antenna but its gain on the lower UHF channels is a couple db lower than the 3023. I've used both and my own tests on channel 17, 19, 21 and 24 confirms this.