Did a XC to Bristol and a GWR one to London last weekend. Both HSTs were comfy, but in different ways. I was able to snooze away easily on both, could've done even if they were crowded. GWR have more legroom, but XC have nicer looking interiors.
Trying to relax on a Voyager home however, was difficult. Due to the cramped seating and random vibrating parts of the train. It wasn't even that busy. Still cant believe they are heavily used on the longest services in the UK. Really hope the IEP is both quieter and has more legroom, (i find the 395s absolutely fine).