I am 46-years-old. I was a pure street skater my entire life. At 43-years-old I "discovered" transition, and man, what an awakening that has been. Wear pads. Knee. Elbow. Helmet. Even on smaller ramps. Minis can bite, and bite HARD. You don't have the time to react the same way you do on a vert ramp. Learn to knee slide, even on smaller ramps. A "run out" that goes bad can lead to very bad twists, tears, and breaks. Bones heal, but damage to the soft tissue stuff (e.g. twists and tears) is what will really do you in. A hard fact of life is that when you get older, you don't react/heal as as fast as you use to. Pads can save your ass. However, there are some things that pads will never protect you from, too (e.g. twists and tears), but if you can get into a knee slide, you take a lot the twist/teat scenario off the table. Take note of the other people in this thread who have mentioned injuries from run-outs gone wrong, or said that run-outs can be sketchy. Knee slides are the way to go.
Q: How is it safer than skating ledges, flat, banks?
A: Safe is a relative term. The bigger the ramp, ledge, rail, etc. you're skating, the less safe it becomes. Knowing your limits, and how to break down tricks into smaller parts is also incredibly important. Jumping around a lot (e.g. ollies, street skating, etc.) can really wear your joints down. I certainly feel it after a day of "hard" street skating. If, however, I skate a mini ramp all day, I am a lot less sore, and my knees/ankles don't hate me as much. I am not sure I would say I find transition "safer," but it is absolutely less of a strain. I will be carving bowls long after I have stopped doing nollie kickflips, etc.
Q: Are there any techniques that make it easier to bail besides the obvious knee slide thing?
A: Knee slides are the best way to bail on ramps, esp if you're in the older crowd (where run-outs become more precarious). They are actually a lot of fun, too.
Last, transition skating will help your street skating. I never would have done that b/s disaster in my sig file, at 44-years-old, if I hadn't started skating more transition.