iPhone 6 is on 8.1 and running fine. The only thing wrong with it right now is almost certainly related to the SanDisk TLC NAND it has, and that's not going to be solved by 8.1.1 according to anything I've read or info others have posted on that problem. If there's a software fix for it, it's not out yet, so why bother updating?
rMini is on 8.1.1 stock...which mitigated most of the WiFi issue, but no, it doesn't solve the occasional stuck keyboard or a host of other bugs. There's really only two or three tweaks I miss on that device, and I've lived without them for 2 months already. I'd be more tempted if there was an adequate biteSMS replacement, but since there isn't, I'd rather be able to quickly update the firmware the second we find out Apple's finally gotten around to fixing this buggy piece of crap they call firmware.
Even if I were to want an 8.1.1 JB, I've yet to see anything from anyone stating that yes, they've examined the code and are confident there's nothing malicious in there to be concerned about. I don't use jailbreaks until that happens from a reputable source. While I tend to doubt there'd be anything in the JB itself, this is a "rather be safe than sorry" issue for me.
Probably waiting until 8.2 or higher to update and re-jailbreak, at the rate Apple is going as far as implementing bug fixes...