I can certainly attest to feeling that Southwest flights in general taxied faster than most others I'd been on. Occasionally it feels like that on some other airlines as well. There seems to be a sort of "normal" taxi speed, or one that feels normal to me. Then there are times when it feels like we're going faster than that. That's it, not unsafe at all or anything. Pretty sure I've experienced a turn or few with thrust reverser on taxi as well, not sure what airline(s).