Hi, welcome to the thread.
Just to mention; off road riding doesn't really require the same capacity bikes as road riding, so many riders coming off road machines of 600cc plus can feel the need to stick at a similar capacity. This can be a big mistake for the rookie who's about to head out and scare themselves on their new rmz450 or Ktm530sx!
You mention the 400, but maybe a 250 would better suit your needs to start with? That's not meant to sound like a criticism or anything, but may change your perspective on bike choice....
Neither the 400 or 650 will tear your arms out their sockets or get you into too much trouble, as stock bikes, but their weight may prove to be less than confidence inspiring for a new off road rider.
You dont mention your size and weight either so factoring this in is important too. As a little xl100 isn't going to pull kimdotcom around too effectively!
Maybe some help there? Happy shopping!
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