As I undestand it, scxca partly paids are same as fpos except that they are only paid up to 3c rather than 5c like the fully paids. This means that at some time the company can ask for the other 2c to be paid up. Personally I can't see it happening soon while the chairman has 12m of them ....
There is no expiry date so no time degradation to worry about
Better leverage than the FPOs IMO
Zinc