I use the "Paws Aboard" for my 105lb Black Lab/Rottweiler mix.
It works VERY well and has withstood 3-4 seasons of him jumping off of it (not supposed to let them jump off the ladder as the ladder being used like a platform).
Cons: Its cumbersome and clumsy. Takes a few minutes to set up. Its expensive. No support from the company - when a clip broke after the warranty period, I called and they told me to go fly a kite - wouldnt even sell me the clip, recommended buying a whole new ladder! When the ladder is up, you cant use your swim ladder, have to climb outdrive (dangerous and not recommended). Needs readjustment often.
Pros: It works. People see our dog using it, and think we're the coolest dog-owner in the state.

Yes, I would buy another - albeit hesitantly, if our Paws-Aboard ladder completely breaks one day. I say hesitantly because they are expen$ive and the customer service sucks. BUT as far as I know, there isnt a good reliable affordable alternative thats like it.