I had 1.25 wheel adapters on my jeep.  I bought new wheels with a 3.25 backspacing and don't need them anymore.  I was wondering if I put them back on, would it create undo stress on my differentials?  Also are there any advantages of having a wider wheel base?  

i think it's your wheel bearings that will suffer the most.  also, front end components and wheel studs.

wider wheelbase is good for stability, on road or sidehill.

i don't think it's worth it to run the spacers though.

my 2 cents.

Pete