When i have my fathom set up in the tech configuration (onboard 50s) I have a necklaced reg and a 7 foot hose. I have zero issues. But I also still use the first generation length loop hoses Charlie put on the units that are longer than the current ones he puts on them. I went to the shorter ones and actually didn't like them as much.
Here is literally the one scenario I ever used the bungeed reg because I've never had a caustic. Doing a dive at orange grove I got some duckweed in my bov that I thougth I got out before heading down for the dive. After about 200ft into the cave I realized some of it was still there and annoying the hell out of me. Switched to necklace and purged and shook the bov for a few minutes and got the duckweed out. But yeah, I doubt I will ever need that necklaced reg, but at least for me its easy to use with the loop