Good point. I'm always looking for the outliers -- the heaviest shafts for their spine. And the heaviest 11/32 will weigh more than the heaviest 5/16 if they're both spined the same.
The advantage, again assuming this block works, is that by compressing a high spine/high weight 11/32 shaft, the result can be a spine and weight that's higher than one can find in 5/16 shafts. For example, though not terribly common in 11/32 cedar, I shoot 70-75# shafts. Aside from Sweetland type forgewoods, I've never seen a 5/16 cedar shaft spine that high. Thus, if I could compress my heavy spine and weight 11/32 shafts, I'd have a spine and weight higher than I could get in normal 5/16 shaft. That's what I was trying to get at when I said you could increase spine and weight.
The only way I can get 5/16 shafts as heavy as I want them in spine and weight is to compress 11/32s. I think I'll just use hardwoods instead (L0L).