I know I am a AC guy but its summer and I'm board so here are some more thoughts about some of the responses.
The only skids I know are the TS, Kmod and stock so I can't say on the others.
Some things to think about, I never even heard of Kmod until the last few years but t-sled was around for a very long time, and has a lot of loyal followers. My experience of t-sled skids is that a well valved and setup AC skid will do more than the old t-sled skid, IMO don't burn me for saying that but I have proven it over and over, but the t-sled skids where not mine and the owners may not have set them up right so that might have been a problem. Kmods/Kevins customer service has been great, always returned my calls even answered the phone not during hours when I was just planning on leaving a message. I hear good things about t-sled but so far my experience with is frustrating, to say the least, I hope I am one of very few that they slacked on.
But the Old skid which many are referring to is now outdated with t-sled coming out with a completely new skid, untested by the average user so even if your considering getting one I would hold off for a bit and see what it brings, it seems to have some strong points but there are a few things I don't like and would have to see it work against a kmod before getting interested. We will just have to wait and see, but good for them for stepping it up. I would much rather have a reworked AC skid over the old t-sled skid, the only option here would be the new one.
With the KMOD (cheap package) I noticed it made my HCR feel a little more planted ( I could adjust it to do anything but with the cheaper setup I just left it in the middle for all around use most of the time) it felt a little harder to handle on slight slopes and flat ground but on the hill all I noticed was huge improvements in control and was easier to stay on the snow. I jumped on some other sleds here and there (TM8's) and the handling kinda seemed easier on the flat and slight hill sides but it didn't do near what the Kmod would. It is also very important you set it up right for your riding. With the cheaper kmod conversion it was slightly limited and have been assured with the full kit and raptors it is far better, but don't let that fool you about how much more capable it is over stock. The added height made it so I could sidehill a lot steeper hills keeping the running boards off the snow better (there are some that say a Cat wont sidehill as steep as a PRO rmk, maybe?? but I never had a problem). With that said I was sidehilling this summer in snow that there is no way I could have with a stock skid (the track would have been in the air) and once setup right and you get a feel for it, it is easier to control even though it somewhat feels planted at first. Its just a matter of knowing how to manipulate its handling characteristics.
One thing about it is some of these skids hold there value and you could flip it pretty easy if its not to your liking.