Rich, I'd keep the two 410HLF's and change the head. I personally wish the 810 was two 410HLF's put together. The OLD 810HD Ultra was an attempt at it. The ported 410HLF puts out nearly as much air as a FULL 810E and is LOUD compared to what HALF an 810E will do. The 810 is of course louder if you have the power to put to it. If you look at an SVT-4PRO or the equivellent in other manufacturers WT-1205 eden for instance. They will do the 4 Ohms in the Stereo mode and will ROCK a set of SVT-410HLF's, also in the stereo mode they will handle 2 ohms and four cabs if you decide you need to upsize. I'm working on trying to figure out how to stack an 810 with a 410HLF to get a 6.5' stack. Anyway, the 410HLF ONLY, none of the other cabs only the HLF is actually a better cab in my opinion than the 810E and I have a pretty good knowledge of both. I personally feel the SVT-410HLF is the best cab Ampeg has built. BOB