I have a B17 on my LHT.

I'm around 140lbs and find it pretty comfortable. Having said that it still gets a bit uncomfortable if I have the majority of my weight on the saddle for extended periods of time. When I'm pedalling normally the saddle is a non-issue as a lot of the weight is on my feet. So maybe the Flyer is better for a sit-up bike.

Remember that even the base B17 'flexes' when you push down on it, so there is already some suspension on the standard saddle.