I've owned one Arm & Hammer anvil, and didn't care for it at all. The one I had was 132lb, and was dead as a doornail. There could have been a number or reasons.... it MIGHT have been through a fire, or who knows what..... but when you dropped a 1" ball bearing on the face from about a foot or so distance, it was like dropping the bearing on concrete...just kinda went "thud" and didn't rebound. It was totally my fault....because I purchased it when I was traveling across the country, and bought it without "testing" it.
The test I always use (after I made the above mistake) on anvils is to drop a 3/4"-1" ball bearing on the face from about a foot above the face.... a "good" anvil will rebound the bearing back to (or very close to) the height of your hand. The distance the bearing rebounds will give you a direct indication of how easy or how difficult the anvil will be to work with..... more rebound from the bearing means more energy will be transferred into your work piece, with less effort requried from you. A lesser amount of rebound from the bearing indicates that you will have to hammer more/harder to achieve the results you want.
In general, lesser bearing rebound is an indicator of a "lesser" quality anvil, whether that be from a manufacturing standpoint, or as I mentioned an anvil may have gone through a situation (such as a fire) that tempered the anvil beyond usefulness. Either way, using the test has saved me from bidding on, or owning, what would otherwise be an expensive "rock".