This is a 2022 update from Theo Gallus about his population of RES X BG hybrids. Thank you Mr. Gallus for your HBG advice and update.
""I'm in the middle of Ohio. One of my ponds has SMB, YP, a few CC, and a very healthy, larger than I want (in numbers, but growing impressive in size) population of BGxRES. The latter were not stocked as Specklebelly Sunfish, but are rather the result of adding about 4 dozen male only BG to a breeding population of RES in 2008-2011. There may still be some pure RES left in the pond, but I can't swear to it, as the BGxRES (now in Fx generations that have an interesting mix of characteristics) are much more aggressive wrt taking feed and being caught.

I find BGxRES to be wonderful IF you have the predators or time to control their numbers. My SMB/large YP/CC predation is not sufficient to keep the BGxRES numbers where I want them, so I remove about 500 BGxRES by angling every year from this 1/2 acre pond. (Roughly 1/4 to 1/3 of these are eating sized - 6 1/2" to 9"; I return all BGxRES 9" and larger, with a current BGxRES record of 13.25" and just over 2 1/2 pounds.)""

Here is a very good YouTue video about the best guess for identifying hybrid sunfish.