Thank you all for the input. As Jun pointed out there is very little difference between a front roll and a breakfall and I'm usually ok if it's a choice between those two. Then it's only a matter of whether or not my lead hand is available. It's the choice between a back roll or a forward breakfall (again, I'm thinking of iriminage) that screws me up (I've been told that there is no difference between those either but I'm not at a point where I see that yet
To give you a little more background (and to address Ron's point), I'm recovering from an injury, so I'm trying to be selective about my breakfalls. On the flip side though, I don't want to get hurt worse by not taking one if I do need to.