How do 2-3 FingerTrees generalize to bigger branching factors? FingerTrees as implemented by Haskell's Data.Sequence use a branching factor of 2-3 for Nodes, and have Digits of size 1-4. Imagine we want to make the branching factor much wider -- perhaps to amortize per-node overheads better, or to improve lookup performance at the cost of update performance. 

For example, we might want branching factors of 31-32 as in RRB-trees, or branching factors of 16-32 as in B-trees. How should the size of the Digits change to accommodate these branching factors? More generally, are there algebraic conditions on the size ranges of Nodes and Digits which are sufficient to guarantee the asymptotics (logarithmic access to the middle; constant-time access to the ends) of FingerTrees?
Yes - if you read the original paper and assign the notions of safe and dangerous digits to the smallest and largest digits, the math should all go through.