JA Pulsars vs Harbeth 30.2

Something I wish I knew ahead of time-

You should check to see if the JA Pulsar model you are interested in has a Magnesium cone woofer.

i purchased a pair of Opera Callus bookshelf speakers that have SEAS  Magnesium cone woofers. The speakers sound wonderful. However, over time the magnesium cones have corroded. (Magnesium is a highly reactive metal) A Google search confirmed that others have had the same problem. SEAS claims that the corrosion does not affect the sound. I hear no difference.

The problem is that I cannot sell the speakers if I want to change my gear. Would you buy used speakers with corrosion on the woofer cones?

As macg19 said, the magnesium cone speakers are used by JA. 
Harbeth does not use magnesium cones

When buying speakers you do need to listen whenever possible. As I mentioned earlier I have the Opera Callus speakers that have the SEAS magnesium cones. They are similar in size and look to the JA Pulsars and I loved the sound of the Callus speaker.

I have always liked the sound of the Harbeth speaker as well and earlier this year I found a used pair of Harbeth SHL5 on USAMart for a very good price and purchased them. I listened to both speakers side by side in my listening room for many days and to my ear the Harbeth was a little bit better. I could very easily live with either speaker.

To me the best part is looking for the next piece of equipment. Good luck!