Depends on which 09 rockhopper and how much use it’s had.

I had an 09 expert which was an awesome ride and very light for what it cost.

If you’re talking £400 then that might be considered a bit much for a 4 year old bike that originally cost a little over £800, unless its in extremely good condition with little wear on the components or if its had some upgrades/replacements

For example: http://singletrackworld.com/forum/topic/specialized-rockhopper-expert-2009-19-for-sale-mint-condition

If I were you I’d avoid the carrera (they’re all shite) and the specialized in that price bracket are a bit pony, they ride nice but the componentry lets them down. I’d say this of the more recent rockhoppers as well tbh.

The Bantu seems like a good deal (at that price it’ll be a joe murray approved design, rather than one of his own) but you get shimano hydraulic discs and a 120mm travel airfork.