A few rather positive conclusions can immediately be drawn from this scenario. The dwarves are portrayed as staunchly traditionalist and very patriarchal. In order to get along with the humans a slightly more relaxed tone is helpful and given that these southern outposts had to fend for themselves they are likely more pragmatic than their northern brethren. Also, being colonies they are likely to be less self-supporting and thus more prone to accept trade with the humans. And finally: with a common ancestry but local isolation we have a good explanation for small cultural differences which can provide interesting political conditions to create more depth in the game.
The dwarves of Danea then, were invented mainly to fill the role as "hobbits" - putting a face on a familiar term present in so many other fantasy settings. Since I really didn't want another race (see this blog post) having the hobbits to be dwarves with a different culture felt like a good compromise. Keeping the rural image created by Tolkien gave a pretty good idea what was needed, and given the migration story it was easy to picture the hobbits as just another dwarven clan that had changed more than the others.
Explaining that change seemed a pretty easy challenge; given their strict social hierarchy it seemed plausible that new customs and traditions could have been created from overthrowing the original order - in this case through the failure (death) of the clan's leaders. This would push the clan further away from the other clans, speeding up the cultural transformation. We get a good foundation for adding depth and also for material to help develop a dwarven character's sense of self!