I haven't used any of these, but they all look interesting. The
Rock Exotica Bi-Wire is strong (30, 10, 9 kN), heavy (67g), but most unusually - it has two gates. The inner gate opens inwardly and the outer gate opens outwardly. It looks like it might take some getting used to clipping it, and wouldn't really be suitable for use in a quickdraw, maybe as a more secure clip to an anchor?
Next is a
Petzl Ange, which has been out since last year but doesn't seem to be widely distributed in UK stores. It has a single pronged wire gate (they call it a Monofil) rather than the normal 'looped' wire gate which means it's quite light (28g). For me, I like the idea of a single prong because it cant get tangled up like a normal wire gate - when carrying a full rack I've sometimes found wires from nuts, or the wire gate from another carabiner, can get jammed quite badly in between the nose of a wire gate carabiner. This is very difficult to solve when hanging on with one hand, and can make it impossible to place any nuts because it completely disables the gate.
Last is the
Kong Ergo Wire which has an 'ergonomic' plastic grip on the wire and a via ferreta style locking device.
Imamge from
Kong