I used to have a 2007 Endro SL, I owned it for about 2 years.
You are making a wise decision upgrading the shock, if you are running the stock AFR then it is a pile of turd I’m afraid, anything will be an upgrade.
The Enduro SL is very active, it’s difficult to get rid of pedal bob. I had a DHX5 with a titanium spring, it was extremely plush on rough stuff, but it was difficult to remove bob even when running 25% sag with the pro pedal almost maxed. I would look at something with better platform damping like an RP23 or Monarch Plus, the Monarch felt like an awesome shock when I ran it on my current bike (Covert).
edit: didn’t realise this thread was 6 months old.. duh!