With the recently added tag fields, especially content grouping, the current tag size limit is unfortunately inadequate to accommodate a reasonable amount of information made possible by the supported tag fields. I imagine there is a hard-coded limit somewhere that is easy to change, but I don't know how changing the limit will impact rockbox in general. If I understand correctly, this should not impact users whose tag sizes are under the limit since the allocated tag size is not fixed by the limit.
Is it do-able? Does it constitute a valid (i.e. likely to be accepted) feature request? If so, I think I'll throw an entry on the tracker.
Thanks