To get back to the OP's question, I can't say for sure whether the Sony cameras will satisfy you coming from Epic, but I did myself choose an FS7 over a used Scarlet Dragon, and I feel that it was ultimately the right choice for me. Versatility-to-cost ratio was probably reason number 1 (built-in ND filters, ease of throwing it on my should, ability to use mount adapters/speedboosters, good codec, 180 fps in HD, built-in XLRs, long lasting batteries, etc.). And I too shared your concerns about the weight of a rigged Red as well as the additional costs of building a usable package.
But then, a big part of the choice comes down to taste -- if you just plain don't care for the image out of the Sony, be it FS7 or F55, then most of the other benefits of switching probably won't add up for you. I've found forerunners in the Sony line (FS100, FS700, FS700 + 4k RAW recorder module) practical to use, but I had never loved the image from this series until shooting CineEI/Slog 3 with the FS7. Combined with the XAVC codec, you get very good color and some latitude in post, and the LC709A LUT (the "Alexa" LUT) usually gets me pretty close to where I want to be pretty quickly.
If you want something even smaller as a B-cam/gimbal cam, I'd also suggest taking a look at the new FS5 rather than rigging up an A7S/RII. There are early reports of software bugs, but maybe give it a little time and then see for yourself-- there are limitations, but it's a lot of camera stuffed into a very small and inexpensive body, and with a lot of the practical conveniences of the FS7.
But then, a big part of the choice comes down to taste -- if you just plain don't care for the image out of the Sony, be it FS7 or F55, then most of the other benefits of switching probably won't add up for you. I've found forerunners in the Sony line (FS100, FS700, FS700 + 4k RAW recorder module) practical to use, but I had never loved the image from this series until shooting CineEI/Slog 3 with the FS7. Combined with the XAVC codec, you get very good color and some latitude in post, and the LC709A LUT (the "Alexa" LUT) usually gets me pretty close to where I want to be pretty quickly.
If you want something even smaller as a B-cam/gimbal cam, I'd also suggest taking a look at the new FS5 rather than rigging up an A7S/RII. There are early reports of software bugs, but maybe give it a little time and then see for yourself-- there are limitations, but it's a lot of camera stuffed into a very small and inexpensive body, and with a lot of the practical conveniences of the FS7.