Maybe floppy problem is with detect low or high density. Most of the FDD does not have switch for switching between low and high density.  Some FDD - especially older have a switch e.g. SAMSUNG SFD-321B/LEB (LEB series). Apparently this is one of the better FDD. Please look at this forum about LEB series that solve problems with CPCdiskXP:
 
http://speccy.pl/forum/index.php/topic,911.msg12437.html#msg12437
http://speccy.pl/forum/index.php/topic,911.msg10808.html#msg10808
http://speccy.pl/forum/index.php/topic,911.msg10895.html#msg10895
 
Also please read this about FDD SAMSUNG LEB series: 'Read errors handling'