I bought Logitech's iPhone cable to use with my SE846s. I will often get phone calls when traveling and it's a big hassle to take out the IEM while walking through the airport to answer a call. Or maybe I'm at the gym. It's just more convenient.
Not a big believer in cables at all, but I think the stock Shure cable sound a bit more strong in the bass than the Logitech cable. Might be a problem with the Logitech connector.
How does the Logitech cable get the microphone close enough to your mouth? Don't you need to plug it in at the base of the SE846 cable? Sorry I've never seen the logitech cable before.
But I too wish the SE846 had a phone cable.