My Tour included the accent from Belinzona and the descent down to Chironico but there are multiple different versions for those parts so I think the best FKT route is between the first and last hut on the classic Via Alta della Verzasca route which is traditionally done over 4 days.
I think for the FKT the first hut is the logical starting point and the last hut the logical finishing point. Otherwise it is not really comparable because some people take the gondola for the very first part and either descent into the valley on the east or west.
The Via Alta della Verzasca is traditionally done over 4 days (south to north) with one extra day for the accent to the first hut (Cap. Borgna) and the descent on the 5th day into the valley in the west after the last stage. The 4 "days" are my laps 4,5,6 and 7 on Strava. It includes all stops along the way. (2:51:56 + 4:04:04 + 4:06:52 + 2:25:42 = 13:27:54). [Strava shows total time of 21:12:07.]
For my tour I just decided that it would be cooler to do it valley to valley and obviously without the gondola. I had to descent to the east even though it was substantially longer as I would have been to late to catch the last bus at the end of the valley after the western descent.
During my research before I couldn't find any times for a non-stop run. Now I found your podcast and decided to enter my time into your database.
I know that it is possible to do it a lot faster since I lost some time due to route finding and also because I had already done around 2000m of vertical up to the start of the FKT. I would call it a mountain run as it includes a lot of easy scrambling (graded T6- on the Swiss Hiking Scale (T1 to T6)) but it is quite well marked. It would be cool if some more people would go for it.
Trip report (German): http://www.hikr.org/tour/post122370.html