What’s sufferfest like compared to trainerroad?
I would say that feel wise, it seems like a less serious training tool compared to Trainerroad, and is far less flexible in terms of both variety and number of workouts, and the ability to create workouts (ie. Sufferfest doesn't yet do this!). I quite enjoy the videos, but then again I purchased many of them before they did the app so I can still use them with TR.
The 4DP test they use works quite well with the workouts, and I would say it gives (for me!) a more realistic FTP number than the TR ramp test, but then again, if I want a realistic FTP number in TR then I can use the 20 minute test.
I haven't used the strength training or the mental training parts of it, but the yoga vids were pretty good.
I think you'd expect Dan Lloyd to be able to increase his fitness scores quite significantly going from nothing to doing something, regardless of the app he used. I never really used the plans they had, although I did check them out. I would say that the progression within the plans and the purpose of each workout is nowhere near as clear as it is with TR. I think you can see that from the plan for Dan Lloyd. Also, fiddling with your power profile for various workouts to give them a different focus seems a bit shit (this is a new thing for their latest app update).
Having said that, I'm at a fitness plateau whatever I use!