data redundancy or not?

Hi,
perhaps a bit off topic but i realy want to know what you rails people
think of the following situation:

i am building a shift trading application, so i have a table with shifts
and a table with transactions.

in the transactions table i keep track of the movement of shifts between
users. i have the fields from_user, to_user and status the status can be
- offered for trade (1)
- in negotiation (2)
- transaction completed (3)

so, when i take a shift, i can always determine the status of it as
follows:
if there are no associated records in the transactions table, i can
offer it for trade.
i can also do this when there are no transactions with status 1 or 2

of course this is not too complicated to figure out, but adding an extra
status field on the shift recored is much easier to work with.

so: what would you do?
add the extra field or keep the design clean?