Well for me 10k blocks seem to be staking very well as I earn several stakes per day by having my Boat split into 10k blocks just like I have with Rain. It all depends on the network weight as well because some times the network weight is higher then others so it will be harder to stake but overall you should be fine with having 10k blocks of coins for now and then later on you could increase them to 20k blocks as the network weight grows which it has been doing as more people hear about Boat and get in.