Yes the full spool is that much stronger, because the stock carrier that the ring gear bolts to is cast. I have had a Ford carrier for the limited slip break right where the 2 halves bolt together. The inertia weight and overall weight will be less with the full spool.
The other item is that I think that the mini-spools only come in 28 spline or 31 spline. If you are buying aftermarket axles (and I hope you are), they are about the same price for 31, 33, or 35 spline. I have broken 31 spline axles, so I run the 35 spline axles with spool, nodular center, and an aluminum pinion support. The stats say that I could probably have gotten away with 33 spine axles, but mine are 12 years old and no issues.
Bill M