Well I had my first experience of an 800 last week from Bristol to Paddington. Overall I was very impressed, I couldn’t tell whether it was running on diesel or electric (much as that embarrasses me!), the seat was comfy, luggage space adequate, trolley sufficient (and appeared 3 times over the journey), and it rode fairly well!
I rate it as better than an HST because it didn’t lurch sickeningly as it started, didn’t have random drafts from the vestibules, had nice toilets and didn’t make me jump out of my skin every time another train passes...