#1
Is this crazy or not?

Is it possible to interchange different brands of head and speakers?

Any shortfalls or not?

Anyone know good brands of speakers?
#2
as long as you match up the ohms (i.e 8 or 16) and have a cab thats a can support a higher wattage than the head (like a 100w head with a 120 or 150 watt cab) you should be fine.
DIMETHYLTRYPTAMINE
lol
#3
people do it all the time, if you change a speaker essentially that's what you're doing, tha actual wooden box makes no difference to how it works.

Make sure you have the right impedence (i.e. 8ohm out of head goes to 8 ohm cab) and that you have the right wattage (running 200w through a 50w cab is a bad idea)