I've been testing out hosts on Mac for their support for the Ti and so far Studio One seems to provide the best experience for the way I work. I'm mainly interested in stability, latency and rendering workflow - I don't use the Ti multi timbrally or sidechaining so didn't test those things. Here are the comparisons:
Tracktion 5 - unacceptable latency levels, unstable and renders tend to be distorted - also it has an offline "autorender" feature that kicks in as soon as you open a render window if you don't disable it which causes the Ti to switch itself off and I had to restart the whole project to get it working again.
Ableton Live - no realtime freeze/render - you have to render by recording live from a midi to audio track
Logic 9 - acceptable latency, relatively stable, no realtime freeze, realtime render only possible if you export to a file then reimport into project
Reaper - latency is very noticeable, Reaper has a rather unique way of handling audio that reduces CPU load by background pre rendering, so it's possible I if I disabled that and tweaked the audio settings I could get latency up to an acceptable level but then that would impact on other plugins. Freeze seems to be just offline but there is a realtime option in the audio export. Seems stable enough.
Studio One - very stable so far, latency very good without needing further tweaks of settings and what I liked most was it now has (since version 2.5 I believe) a "convert to audio" feature (basically freeze by another name) for each track that automatically determines if the render needs to be offline or realtime - that is a brilliant feature that makes rendering tracks from the Ti a seamless process. S1 also supports for most plugin formats - VST, VST3 and AU and supports them fully (unlike some other hosts that seem to just support parts of the plugin standards)
So as said, not tested how easy it is to setup multitimbral usage of side chaining in S1 but if anyone else has experiences of this please add to this thread. It would be cool if Access made S1 an officially supported host - they seem to have gone out of their way to make working with plugins like the Ti control a painless experience. The convert to audio feature is a godsend.