The Kapex Extensions have enough play in the legs to account for the difference in height of the MFT 800/1080 tables. So they work just fine. Also, see the photos in that post. Hope that helps.
If space permits, why not use the MFT on the infeed or outfeed side of the Kapex? I have modified MFT 800s flanking both sides of the Kapex and it works great. You can see a part of it in my profile pic.