Checkbox field values inconsistent

I'm noticing that custom field types that are checkboxes are inconsistent in terms of how they accept or read values:

For example, on a custom record, if I have a custom field "custrecord_mycheckbox" setup as a checkbox, then 2.0 says I must set this (and assume read) as a boolean:

record.setValue({fieldId: "custrecord_mycheckbox", value: true});
and
record.getValue({fieldId: "custrecord_mycheckbox"}); returns true or false

If I attempt to do set this using 'T' or 'F' like with 1.0 methods, I get this error:

You have entered an Invalid Field Value T for the following field: custrecord_mycheckbox

However, if I add a dynamic field in beforeLoad to the record "custpage_mycheckbox" and type it as a checkbox, and I try and set the defaultValue using boolean, I get this error: