50mm1.2L - worth using for macro?

We just got the 50mm 1.2 at home, and I was wondering if this would be worth using as a macro lens (with tubes). I also have the 85mm1.2L.

This is coming up because my 100mm 2.8 is dying, and if I have to spend the money, I already know I want a macro flash, so I'm hoping I can make use of another lens for the time being.

could I even try the 50 with the 85 reverse mounted?

Thanks in advance!

You can try reverse mount or extension tubes.
1. You don't need a macro flash, your 580EX II should work fine if you just diffuse the light.
2. How did you 100mm 2.8 macro die?

It focuses to infinity if it has to focus more than slight amount. I might take it in for repair, but I want to see if I can get similar results with other lenses and tubes.

In autofocus or manual?

autofocus. It used to work just fine.....now it usually focuses to infinity and keeps going, with a grinding noise.

Hmm... weird. Well, I never use autofocus for macro so it wouldn't bother me =P