Because of strict licence laws for bikes over 400cc in Japan a great many bikes are made in a 400cc version. Including the TA. I recall a couple of aussie guys went across Russia on 400s with no problems.
It has all the features of the 600. In otherwords, it is a fine choice. There have been a lot of happy transalp overlanders.
The disadvantage, if you can call it that, is that the weight, robustness and size of the components are designed for 600cc. So you will be well within the mechanical and electrical tolerance limits, but with less power.
Have you seen any AX1s out there? Another good choice.
There is a functioning web list which will be only too pleased to give you back up advice and support. I can help too. Just ask.
Around the world 2000-2004, on a 1993 Honda Transalp