This is a mod that is really only viable if, like me, you already had the Vantage seats on another kayak. At AUD$575 for each seat it wouldn't be worth it, especially as you don't get the adjustable thigh support.
Still, my wife and I are are very happy with this mod. You certainly sit higher and drier and the comfort and breathability of the seats is a great improvement over what we had before. The under seat storage is an added bonus and they do make great camp chairs as well.
It was actually a pretty simple mod to do. The Vantage seats lend themselves to a number of mounting options. I used 20mm alloy channel sitting in a 25mm channel for quick release so that I can refit the original seats easily if needed. I could have gone with 25mm/1" Bimini tube. The tube would need an indentation for the thigh support lever tab. It may also be possible to use the feet and floor mounts from the Vantage Pro Angler seat in place of the rear saddles I fitted. I'm checking out part numbers with my dealer.
As LB points out the C of G is raised but that is not an issue with the TI. Sitting higher makes it easier to swap sides when hiking out.
It is probably an issue in kayak mode but we've yet to test that.