I use a gamepad and only have 16 visible slots, I can access other 16's easily by right shoulder button. I personally wouldn't use macros on blm and I don't. lets say you make a macro that combines several spells and abilities. What if you get interrupted. Your macro set would be thrown out and as it cycles you cant do anything until its completed. If your cycle is 20 seconds long including spells then your stuffed. Also during this time if you come under attack and need to use defence spells once again the original cycle is still running causing you more grief.
Macros can make life easier but with blm where you cant do much in the way of spellcasting while moving then its going to hurt. Also, lets say you go through a cycle and fire 3 procs, your not going to be able to use that due to the macro cycling.
Hope it helps