i don’t think there’s really any difference on road between grip levels on different tyre patterns, you want completely slick for most grip (on a bicycle). Compound can make a difference, but running a very hard compound is likely to be fastest on a TT stage (as the second lost on the odd downhill corner is more than made up by riding on the flat).
Owning a TT bike, not sure what the comments about handling badly are all about. They handle just fine, your weight distribution is a bit different to a road bike (but its hardly optimal there), otherwise if you have some semblence of talent you can ride just as well on either.
I’ve had exactly that kinda crash on a wet roundabout at the bottom of a hill on marathon plus tyres (so lots of tread) on a touring bike. Simply too much speed for the conditions, and once a wheel is going sideways in the wet the force at which it will re-grip is much lower, so you’re basically screwed