I always like plenty of capacity. In the DP we have a 7.5KW Onan, takes care of whatever we want. For the TT, I'm still trying to decide. I have three Honda 2000s, but carrying a pair of them around doesn't appeal to me, but it might be what I wind up doing.
Bigger generators mean
More weight - who is going to help you lift it all of the time? Is weight an issue in your truck?
Larger fuel tanks that burn fuel quicker - more to buy and haul
Takes up more room
Costs a lot more - I think a Honda 6000 is a little over $4,500
More expensive to repair
What else?
Bill