Hi I was wondering should I go with 29's calmini SR and EMU Springs (I think this is around 4' of lift)
or
My friend has offered to trade my calmini SR for a SPOA (front drive shaft in the rear, extended brake line brackets, add leafs) Ill put 31s on this.

What would be more cost effective and reliable, do 31's destroy parts?

For 31" tires a SPOA is a great way to go.  But you will need to drop your t-case gears to make up for the larger tires, otherwise you just won't have enough power without an engine swap.  If you wheel it a lot you really should look at a traction bar for the rear to avoid spring wrap.

As for destroying things, it can.  I ran for years with 33" tires without destroying anything with a spool in the rear and ARB up front.  The guys I wheel with destroyed plenty of axles with 31" tsl's and lockers front and rear.  So it all depends on how you drive.

I say run until you break something, then upgrade to Chromoly axles from Trail Tough. 

are those chromoly axles better than the toyo axle and housing?

No, but they don't require new drive lines, brake lines, spring mounts, steering parts and 6 lug wheels.