We have been using CBS for 4 years now, and we started off with an IR spot. We had exactly the same problem. Owners would ABUSE the IR roster spot, until one week cbs just dropped non IR players in IR spots automatically in the FA pool (then owners became gun shy about using IR spots, lol) I would warn your owners about that. I ended up having to patrol the IR lists and rosters and just became too much work.
We ended up using a flex bench spot that owners could use as they wish. Less headaches trust me