I have tried to envision each of the description each of the ukemi descriptions. Words are hard to imagine. So, since Janet mentioned my DVD, here's the link
The advantage with starting with breakfalls:
1. Although counter-intuitive to aikidoka, that's how judoka start, so it's not an innovation on my part, by any means.
2. The problem with most people's rolls is that they do not look over the opposite shoulder. This a) is bad enough with a roll, because you end up rolling over your shoulder and hip, which, unless you have tendons like cables, will soon result in injury b) breakfalls will be even more dangerous.
3. When you learn a proper breakfall, you will have the following habits: rolling over muscle rather than joints (shoulder blade-small of back); as Phi mentioned above, your head will be very tight to your arm, which vastly lessens the need for "survival breakfalls" when you have an inept or malevolent nage c) even when you take a breakfall, it becomes, essentially, a "roll in the air" - with your arm tight to your head, looking over the opposite shoulder
4. Because proper breakfalls are the first reflex you learn, you will not fear ukemi at all - - - roll/breakfall - its a matter of the best thing to do, not something you have to gear up to do.