I recently got an X-85. As far as I can tell the differences between it and the x-85 are that they added a temp sensor into the transducer and changed the style of the buttons. Based on the picture they now have an 8 direction cursor movement button/pad where the x85 had four separate direction buttons. I would guess they've changed the user interface to take advantage of the diagonal direction capability.

I read somewhere that they also now offer a wide angle transducer. I think it's a 60 degree cone compared to the standard 20 degree cone that came with the x85. The 60 might be good if you only fish shallow water. I think the 20 degree still comes standard with the x91, but not sure. I think they still offer the 8 degree transducer for the deep water only people. The x85 had a form for swapping the standard 20 degree transducer for an 8 degree one at no charge.

As far as speed transducer, I haven't seen it in writing, but it has to support it. I would guess it also supports a couple extra temp sensors for air temp, live well temp, bait tank temp, etc. My x-85 supports up to 3 temp sensors in addition to a speed sensor and the transducer.

I love my x85. Excellent image and even though it's got a 3000 watt output, the clicking (I can hear it in my 12 foot aluminum boat without decks) is quieter than my old 375 watt humminbird. The one issue had with it was that it was so sensitive that my trolling motor induced noise on the screen. I'm running a infinitelt variable speed trolling motor off the same battery as the x85.

To fix the noise problem, I ran a small lead from the negative post on my battery through a 0.5A fuse to the hull of my boat. That took care of the noise (eliminates ground bounce due to the pulse width modulation in the motor controller by tieing ground to the lake). The key is that the this lead has to connect to a low resistance path to the water. The fuse is very important in case any 12V wires get worn through and cause a short to the water or the hull in my case. Wouldn't want to arc weld my trolling motor power cable to my hull or worse yet have it burn a hole through my hull.