I have worked with several American Water Spaniels. I took care of about 9 of them for about 4 mo.s. I would have trouble recomending them to someone who is seriously looking at a Springer or a Lab. They are a breed suited for those hunters that want something that hardly anybody else has. I have personally never seen one smaller than about 35lbs. I dealt with dogs from the 2 largest kennels in the USA so I think I have seen a healthy sample of them. They are not as quick to learn there lessons as other breeds. They are slower to mature, and you can not pressure them at all, or else they will refuse to do the easiest things. There are some good ones out there. I personally have not seen nor hunted with any. I hunted with a fellow for a couple years who had 2. They were the same age within a day of my Springer. We trained together quite a bit. He had a Female that would do water retrieves, but was very slow at them. She also could not mark a single bumper even if it was tossed 20 feet in front of her. She would swim around and around until someone tossed enough rocks to lead her to it. Meanwhile my Springer would be starring at it wanting to be sent. If his gave up I would give the command and my Springer would launch so hard she would just about land on the bumper. His other female AWS would not even get in water on a hot day. Low drive to be certain.
I thought that maybe it was his training methods so I worked with the dogs. They just did'nt seem to have any drive, nor where they very biddable. To sum it up I have just worked with a handful of these dogs, so I may be wrong.
Just be sure to get your facts from some people besides the breeders. The breeders are a dedicated lot who will sell you on there good points, but may not be so eager to show them at work.