For the Reservists, has traveling Space-Required worked when going on IDT?

I'm just reading up on the options available for Reservists. One of them is using Space-R in lieu of travel reimbursement. Given that reimbursement is dependent on unit-available funds, would it be a good idea to use Space-R first, and reimbursement when absolutely necessary?

http://www.spacea.net/faq/reservist