Without any priority mechanism an author can still ensure
{number:[0-9]+}
gets all numeric paths before
{varname}
gets everything else, by replacing it with
{varname:[^/]*[^0-9/][^/]*}
(which requires at least one non-digit).
So it does “allows complex things” without a priority attribute.
> sort paths with explicit regexs ahead of those using the default
Good idea (as a secondary key, after number of literals).