In my opinion, these type of ladders look a lot better than they perform. Problem is that being flexible and not having standoffs allows the lower rungs to move under the bottom of the boat making it very difficult to support your weight by your legs and if you don't have a lot of upper body strength it could be a real struggle to get up one of these. With out standoffs your toes get pressed hard against the hull which is painful, but better than drowning. I am familiar with the concerns of using the stern ladder on something like a Sun Cat because it is angled backward and doesn't have much to grab onto to pull yourself up, but I would prefer it to one of these ladders. I'd probably try it out before it was needed for an emergency. I do believe a boarding ladder of some type available to be deployed from within the water should be mandatory. It's funny but not funny the number of people who have jumped off a boat to enjoy a refreshing swim, only to discover to their horror that they have no way to get back on board, sadly many have perished.
Other than the standard stern ladder, I have had great success with what is called a dive ladder which comes in two or three step models. They are easy to climb and can be inverted in their transom mount when not in use. They can be easily dismounted and inverted for use from within the water, and they float. They are especially useful when you have minimal space to mount a ladder on the transom, but should be used with a backing plate as the mount has a small surface area.