... 587 and 673 are very desirable as sharing the MM inscription on dial. This is a very attractive detail for Paneristi I feel.
In any case I find the 587 and 673 have quite different personalities: the 587 is more subtle and delicate, the 673 has a more brutal or stronger look and with the crown bridge most people associate with the brand.Both have their own charm!
I haven´t seen the 720/721 in the metal yet. But I like them so much.
The 720 with inscriptions reminds me of the 232 which I like so much but I never could find one for my collection. The 721 is very attractive as a replica of a German swimmer watch.
I have not decided which of the two I would buy, but definitively I will go after one of them.
Both are storical models which is what I specially like among the many different Panerai models offered by the brand.
Cheers! Abel.